PDA

View Full Version : Which Oil?



mr bidd
04-01-05, 04:22 PM
Hello,

Does anyone have a Rover V8 engine in their Cobra? If so, could you tell me what oil you use and what oil would you recommend please. Thanks Chris

TINKA
04-01-05, 05:23 PM
Hi Chris, the consensus of opinion by a mile is Valvoline 20W50.

Miket
04-01-05, 05:28 PM
Hi Chris, the consensus of opinion by a mile is Valvoline 20W50. Valvoline 20W50 Racing Oil. :thumb: :thumb: :thumb:

Put my oil pressure up by 10 PSI, compared to Castrol. :confused:

David Large
04-01-05, 06:30 PM
Agree with above. The guy who built my new engine isists on Valvoline oil.
David Large

STEVE G
04-01-05, 06:35 PM
Valvoline Racing 20/50 is the way to go.Much cheaper than most regular oils aswell.Search valvoline site for stockists.

stevee8
04-01-05, 07:00 PM
If you find it difficult to get Valvoline racing oil, Valvoline Turbo V is worth a look, may be easier to source and is cheaper. Despite the name it is suitable for turbo and non turbo engines and has the properties to keep the old Rover alive and well. See more on http://www.valvolineeurope.com/index.asp?pageid=b2f61278c93a4024b4f0a1cfb32f78d2.
Due to the age of the engine design, mineral oils are more favoured than synthetics.

mr bidd
04-01-05, 07:06 PM
Thanks to you all for your advice, I will go out and get some. Chris

osgood
05-01-05, 08:10 AM
Could also try Castrol SAE 40 or 50 (XXL-GP50) they are mineral oils for the older sports car engine and will also increase the oil pressure by 10psi hot, Millers do a similar application. But these oils are of a low detergent type so regular oil & filter changes are required Osgood :angel:

madjohnny
05-01-05, 06:38 PM
Have been in touch with Valvoline today and they inform me that the "old" Valvoline Conventional Racing oil 20W50 is now being badged as Valvoline VR1 racing oil 20W50.

Just for info & applogies if this has been repeated elsewhere. :thumb:

mr bidd
05-01-05, 07:06 PM
Thanks for all the info. Does anyone know if this oil is available generally or if any specific shops sell it eg. Halfords etc. Thanks Chris

madjohnny
05-01-05, 07:11 PM
I have a Halfords right by me but this was not one of the local distributors Valvoline gave me. Motorvation was one, don't know if this is a Nationwide chain or not.

grandadboats
07-01-05, 04:25 PM
Has anyone experiencwe of Active8?

Does it do what it says on the tin?

stevee8
09-01-05, 03:21 PM
Ref John's post, Valvoline do a number of types of racing oil. I thought that the VR1 was a semi synthetic and was not the same as the old mineral oil.

gd02 cob
09-01-05, 05:26 PM
I'm just about to put Royal Purple R41 in my SBC, I'll let you know how I get on.
Nick

Andy S
09-01-05, 05:51 PM
I e-mailed Real Steel re this subject and they have responded re my 69 chevy to use any 20W50 mineral oil. Hope it helps :p

Miket
09-01-05, 08:29 PM
I e-mailed Real Steel re this subject and they have responded re my 69 chevy to use any 20W50 mineral oil. Hope it helps :p Sorry Andy, but Valvoline is far superior to any other oils I have used, Real Steel staff are a set of plonkers, they are never ever consistent with the information they supply. :whatever::whatever:

osgood
10-01-05, 09:47 AM
Sorry Andy, but Valvoline is far superior to any other oils I have used, Real Steel staff are a set of plonkers, they are never ever consistent with the information they supply. :whatever::whatever:
WHooooo Mike bit strong mate ;) Eric

Miket
10-01-05, 10:38 AM
WHooooo Mike bit strong mate ;) EricI learned it from the master ;) ;) :thumb:

osgood
10-01-05, 10:57 AM
I learned it from the master ;) ;) :thumb:
There's no fool like an old fool Mike Eric :angel: :rolleyes: :thumb:


_____________________________

undefined
Get in touch with yourself by touching yourself. If someones looking stop doing it! ;)

calnonp
17-01-05, 11:38 AM
Here is a place local to me which sells it

Merritts of Amersham Ltd
Unit 7, St. Georges Ind Est, White Lion Rd, Little Chalfont, Amersham, Buckinghamshire HP7 9JQ
Tel: 01494 765411

calnonp
17-01-05, 11:41 AM
Forgot to say it's £18 for 5 litres

alastaid
17-01-05, 12:25 PM
I am running on 20/50 from Witham Oils as per the letter in a snaketorque a while ago. Just send an email to cobra@withamoil.co.uk, with the discount it is £46.79 for 25 litres including delivery and VAT. Hope its ok.

Cheers

Alastair

oilman
20-01-05, 02:20 PM
If you are running the Rover V8 you do not need to use a 20w-50, this is giving you very poor cold start protection (80% of engine wear occurs at this time).

Also you do not have to use basic mineral oil, semi synthetic is better and if you really want to treat your RV8 a full synthetic.

It will need to remain thick, ideal grade is the 10w-50 as this provides great cold start and viscosity and hot end protection needed by the RV8.

Cheers

Guy.

mr bidd
20-01-05, 06:55 PM
Thanks Guy, this is turning out to be quite a quest as you have contradicted all the other advice given to me by other Cobra owners. Anyway, I have spoken to a man who builds Rover V8 engines, in fact I've bought a 3.9 short motor from him, he recommends 15/40 Castrol GTX, and only recommends Castrol whatever the grade. He has been building engines for the last 40 years.

Thanks very much all. Chris

russj
20-01-05, 07:31 PM
Hi,


I have been running a 302 with 350hp in my GT 40 for 8 years. In that time I have tried various oils as i always had problems with th eengine breathing heavily. After much research I started using fully synthetic Red Line oil. It is an polyol ester based oil and has much better characteristics than the rest I have tried including the Valvoline. Being a non petroleum base it gives it is also claimed to give 5 times better bearing viscosity/protection.

It is especially good for older style engines where mineral oil is often recomended.

On a hot run to Le-Mans and back last year from Edinburgh I used no oil at all. Where as before with Valvoline etc I was always having to top it up on that type of run.

Various people like Demon Tweeks sell it but you can obtain it cheaper direct from Red Line in Leicster at a cheaper price. They will also happily give you advice on the correct oil for your application, as all they sell is oil!!
I also run there water wetter that has a powerfull anti-corrosion package and definetly stops corrosion of my alloy heads and reduces the temp in the engine. This stops my GT overheating unlike some of the others.

gd02 cob
20-01-05, 07:35 PM
Oil always seems to promote lots of discussion. My engine builder of 30 years experience recommends Royal Purple synthetic. He also suggested Red Line as an alternative.

Nick

osgood
20-01-05, 09:06 PM
Guy & Mr Bidd,

Viscosity

When moving surfaces are completely separated by a film of liquid lubricant, the only resistance to motion is due the viscosity of the lubricant. Viscosity is a property of fluids by which they resist flow: the greater the viscosity the greater the Resistance and vise versa. Thus the "friction" in a lubricated bearing depends depends upon the viscosity of the lubricant. But the viscosity also influences the rate at which the lubricant is squeezed out from between two surfaces when load is applied, IE the greater the viscosity, the greater the lubricant's ability to with stand load. hence the lubricant should have a high enough viscosity to withstand maximum load to be carried without causing excessive resistance to movement.

Introduced by the society of Auto Motive Engineers (SAE) is universal adopted to classify oils according to there viscosities. This method uses a number to represent the viscosity, EG. SAE 20. The higher the SAE number, the higher the viscosity, or to use a more common expression, the thicker the oil.

Whereas engines in the past used a comparatively thick oil, such as SAE 50, the need to reduce both fuel consumption and cold-cranking loads has bought about the common use of thin oils,eg SAE 10. An even better economy can be achieved with the very thin oil, SAE 5, but this can only be used on engines having extra-close fitting bearings; this suitability can only be determined by seeking manufactures advice. Of course we ALL KNOW THE RV8 DOES NOT FALL INTO THIS BRACKET! (SUCH AS FULLY SYNTHETIC OIL).

viscosity INDEX

The viscosity of lubricants decreases with a rise in temperature; the extent of this change is measured by the viscosity index. A high index indicates a relatively small change in viscosity whilst low index indicates a large change. The lubricant used should have a suitable viscosity at its normal operating temperature in the engine. This means when the engine is very cold, the viscosity will be unnecessarily high, leading to poor circulation of the lubricant and excessive friction (oil drag) possibly even to the extent of making the engine difficult to start.

Multi-grade oils

In the passed the high viscosity oil used in an engine during the summer made engine cranking more difficult in winter, so different grades were specified for the two seasons. Nowadays special additives that reduce the change in oils viscosity with temperatures are often used, and this has meant that the same grade can be used throughout the year. These oils are called multi-grade or cross grade, or given trade names that suggest the viscosity remains constant. These oils can be recognized by the special SAE ratting; this has two ratings separated by a "W" . A typical oil is SAE 10W 40: in this case the oil is equivalent to SAE 10 when tested at sub-zero temperatures, (hence the W to indicate winter conditions) and has a viscosity of SAE 40 at the normal rated temperature.

Oiliness

This property is the ability of an oil to "cling" or to be attracted to metal surface. The effect of this property is seen when a spot of oil is applied to a clean surface; the oil film spreads out over the surface and when whipped with cloth. The degree of oiliness varies with the type of oil; vegetable based oils are brilliant in this respect (Castrol R).

Having said all this I think we can say that SYNTHETIC oils and the like should never be used in the RV8. RPI don't recommend it or Reel Steel Osgood:angel:

route66
20-01-05, 09:28 PM
Direct quote from Jim Hand's book "How to Build Max-Performance Pontiac V-8's" page 30. (SA Design / Cartech Books ISBN 1-884089-67-4) (other books in this series include SBC and SBF guides)

[QUOTE]...I also suggest moderately weighted oil for all normal use. Pontiac recommended 20 wt for most applications back in the 1970's. The oil quality today is far superior to that available in 1970, so we certainly do not need heavier oil for protection. Heavy oil adds a parasitic load on the engine through the oil pump, yet does not really improve lubrication. Modern multigrade oil allows us to have superior protection for extreme temperature conditions while minimising the pump load. Weights like 10W-30, 20W-40 and 15W-50 work fine, although I prefer to use 10W-30 in my performance cars.[/quote:b8e23f27f7]
Jim Hand has been building and racing Pontiac engined cars since 1955.

Steve

oilman
21-01-05, 09:36 AM
Thanks Guy, this is turning out to be quite a quest as you have contradicted all the other advice given to me by other Cobra owners. Anyway, I have spoken to a man who builds Rover V8 engines, in fact I've bought a 3.9 short motor from him, he recommends 15/40 Castrol GTX, and only recommends Castrol whatever the grade. He has been building engines for the last 40 years.

Thanks very much all. Chris
Chris,

The 15w-40 grade is fine, however the Castrol GTX is a basic mineral multigrade oil and its lubrication/film strength and shear stability qualities are by todays standards basic.

Castrol make some very good oils, however the grades they manufature apropriate for the RV8 Castrols are pretty basic.

For running in a new or rebuilt engine you will need to use a mineral, but after 1000 miles or so you can move to a semi or full synthetic, keeping it thick.

Cheers

Guy.

oilman
21-01-05, 09:48 AM
Hi,


I have been running a 302 with 350hp in my GT 40 for 8 years. In that time I have tried various oils as i always had problems with th eengine breathing heavily. After much research I started using fully synthetic Red Line oil. It is an polyol ester based oil and has much better characteristics than the rest I have tried including the Valvoline. Being a non petroleum base it gives it is also claimed to give 5 times better bearing viscosity/protection.

It is especially good for older style engines where mineral oil is often recomended.

On a hot run to Le-Mans and back last year from Edinburgh I used no oil at all. Where as before with Valvoline etc I was always having to top it up on that type of run.

Various people like Demon Tweeks sell it but you can obtain it cheaper direct from Red Line in Leicster at a cheaper price. They will also happily give you advice on the correct oil for your application, as all they sell is oil!!
I also run there water wetter that has a powerfull anti-corrosion package and definetly stops corrosion of my alloy heads and reduces the temp in the engine. This stops my GT overheating unlike some of the others.
Redline make some great oils, its the ester/pao base stock combination that gives these oils the edge. Esters assist the additive pack in a motor oil formulation because they are surface-active (electrostatically attracted to metal surfaces), so they help to reduce wear and friction.


They are fluid at very low temperatures and at high temperatures they are very chemically stable and have low volatility (don’t evaporate away).



They also help to prevent hardening and cracking of oil seals at high temperatures.

However they are very expensive and Redlines european competitors like Silkolene and Motul can be sourced in the UK at a much more reasonable price.

It goes to show that synthetics, chosen corectly are well suited to these old design engines.

Cheers

Guy.

oilman
21-01-05, 10:01 AM
Osgood.

Good factual post you made there, however I have a question.

Quote

Whereas engines in the past used a comparatively thick oil, such as SAE 50, the need to reduce both fuel consumption and cold-cranking loads has bought about the common use of thin oils,eg SAE 10. An even better economy can be achieved with the very thin oil, SAE 5, but this can only be used on engines having extra-close fitting bearings; this suitability can only be determined by seeking manufactures advice. Of course we ALL KNOW THE RV8 DOES NOT FALL INTO THIS BRACKET! (SUCH AS FULLY SYNTHETIC OIL).

EndQuote.

When it comes to bearing fitment the RV8 is not what we would call extra close which means a thicker oil is required, but how did you come to the conclusion that this excludes synthetics?

Cheers

Guy.

oilman
21-01-05, 12:04 PM
People get carried away on the dated notion that thicker oils are better but this is not the case. Thinner oils 10w as opposed to 20w flow much better at start up and therefore provide vital protection when the majority of the wear occurs.

Added to that a 10w-50 is as thick as a 20w-50 when its hot i.e. sae 50.

You need to balance cold start viscosity with high temperature protection. The ideal oil for your cars would be a 10w-50 fully synthetic. Not a hydrocracked oil but a proper PAO/ESTER synthetic that contains no petroleum basestocks. This oil is far more thermally stable than a petroleum based oil because it's designed in a laboratory by chemists and the molecules are of a uniform size as opposed to varying sizes in petroleum based oils.

These special oils are superior in all aspects and more importantly if they contain ester, they are polar which is of great benefit.


Esters



All jet engines are lubricated with synthetic esters, and have been for 50 years, but these expensive fluids only started to appear in petrol engine oils about 20 years ago. Thanks to their aviation origins, the types suitable for lubricants (esters also appear in perfumes; they are different!) work well from –50 degC to 200 degC, and they have a useful extra trick.


Due to their structure, ester molecules are “polar”; they stick to metal surfaces using electrostatic forces. This means that a protective layer is there at all times, even during that crucial start-up period. This helps to protect cams, gears, piston rings and valve train components, where lubrication is “boundary” rather than “hydrodynamic”, i.e. a very thin non-pressure fed film has to hold the surface apart. Even crank bearings benefit at starts, stops or when extreme shock loads upset the “hydrodynamic” film.

It is also important to understand the consequences of using an oil that's either too thin or too thick as they can both be detrimental.

Hopefully this goes some way to explaining:

Surely the thicker the oil the better!



This isn't always true - even when using a petroleum oil. Although it is true that heavier viscosity oils (which are generally thought of as being thicker) will hold up better under heavy loads and high temperatures, this doesn't necessarily make them a better choice for all applications.

On many newer vehicles only 0w-40, 5w40 or 10w40 engine oils are recommended by the manufacturer.

If you choose to use a higher viscosity oil than what is recommended, at the very least you are likely to reduce performance of the engine. Fuel economy will likely go down and engine performance will drop.

In the winter months it is highly recommended that you not use a heavier grade oil than what is recommended by the manufacturer. In cold start conditions you could very well be causing more engine wear than when using a lighter viscosity oil. In the summer months, going to a heavier grade is less of an issue, but there are still some things to be aware of.


Moving one grade up from the recommended viscosity is not likely to cause any problems (say from a 10w40 to a 10w50 oil). The differences in pumping and flow resitance will be slight. Although, efficiency of the engine will decrease, the oil will likely still flow adequately through the engine to maintain proper protection. However, it will not likely protect any better than the lighter weight oil recommended by the manufacturer.


Moving two grades up from the recommended viscosity (say 10w40 to 10w-60) is a little more extreme and could cause long term engine damage if not short term. Although the oil will still probably flow ok through the engine, it is a heavier visocosity oil. As such it will be more difficult to pump the oil through the engine.

More friction will be present than with a lighter viscosity oil. More friction means more heat. In other words, by going to a thicker oil in the summer months, you may actually be causing more heat build-up within the engine. You'll still be providing adequate protection from metal to metal contact in the engine by going with a high viscosity, but the higher viscosity will raise engine temperatures.

In the short run, this is no big deal. However, over the long term, when engine components are run at higher temperatures, they WILL wear out more quickly.

As such, if you intend on keeping the vehicle for awhile, keep this in mind if you're considering using a heavier weight oil than the manufacturer recommends.

Hope this helps,

Cheers
Guy

marc davis
21-01-05, 07:42 PM
Iam just about to put the same in my V8, where do you live. A shop called Moto's in kenley sells it.

Alaska Gray
21-01-05, 07:49 PM
aslong as its 20 50 mineral oil it dos'nt mater about the make as long as its a reputable name do not use recycled oil

osgood
21-01-05, 08:25 PM
Osgood.

Good factual post you made there, however I have a question.

Quote

Whereas engines in the past used a comparatively thick oil, such as SAE 50, the need to reduce both fuel consumption and cold-cranking loads has bought about the common use of thin oils,eg SAE 10. An even better economy can be achieved with the very thin oil, SAE 5, but this can only be used on engines having extra-close fitting bearings; this suitability can only be determined by seeking manufactures advice. Of course we ALL KNOW THE RV8 DOES NOT FALL INTO THIS BRACKET! (SUCH AS FULLY SYNTHETIC OIL).

EndQuote.

When it comes to bearing fitment the RV8 is not what we would call extra close which means a thicker oil is required, but how did you come to the conclusion that this excludes synthetics?

Cheers

Guy.Guy this is just a discusion and you obviosly know your stuff, but when I get people like RPI, Real Steel and I think the other guy in Nunetan D J Ellis say do not use Fully synthetic oils in a RV8 I tend to take there advise as fact. Okay then I will admit I have not taken much notice of synthetic oil rattings but I assume they are pretty thin cattering for the modern engine with blue print type bearing tollerances like a desial engine with a CR of 20:1 say? I know that some tunner's recomened a semi synthetic oil or fully sythetic for the Rover but I am all ears. I just thought I would put a post up re the values of the ratting's you see on the tin, as I myself was not quite sure of what meant.

I get with a very cheap oil whilst I am running in in my 4:6 RV8 MGB spring and pack it out to the right length, 85 PSI cold & 50psi hot, I know the RV8 is high volume as opposed to high pressure but if you recon I would be better off with synthetic I am all ears and I will give it a go. Osgood:thumb:

oilman
25-01-05, 12:08 PM
Osgood,

I understand the mechanics point of view, and would not question their experience. However when it comes to synthetics not being used in the RV8, it is a myth.

Have a read.



SYNTHETICS vs MINERALS

Oil is the lifeblood of your vehicle's engine. For decades conventional petroleum

oils have been providing adequateprotection for all of our vehicles.

The key word here is adequate. Petroleum oils, for the most part, have done an adequate job of protecting our engines from break down. If you change it often enough, you can be relatively sure that your car will last 100,000 to 150,000 miles without a serious engine problem - maybe even longer.

The real question is, why settle for adequate when something better has been available for

about 30 years?

Today's engines are built for better performance, and, although petroleum oils are designed for better protection and performance today than they were 10 or 20 years ago, there is only so much that can be done. Today's engines need high performance lubricants, and the only true ones available are synthetics.

Conventional petroleum oils are insufficient for use in today's vehicles primarily because they are manufactured from a refined substance, contain paraffins (wax), sulfur, nitrogen, oxygen, water, salts and certain metals. All of these contaminants must be refined out of the basestock in order for it to be useful for use within a lubricant.

Unfortunately, no refining process is perfect. Impurities will always remain when any refining process is done. It simply isn't economical to continue to refine the oil again and again to remove more impurities. If this was done, petroleum oils would cost as much as synthetic oils do.



There are many components of petroleum oil basestocks which are completely unnecessary for protecting your engine. They do absolutely nothing to enhance the lubrication properties of the oil. In fact, most of these contaminants are actually harmful to your oil and your engine.

Some of the chemicals in conventional petroleum lubricants break down at temperatures well within the normal operating temperature range of your engine. Others are prone to break down in these relatively mild temperatures only if oxygen is present. But, this is invariably the case anyway, especially since oxygen is one of the contaminants within petroleum basestocks.

These thermally and oxidatively unstable contaminants do absolutely nothing to aid in the lubrication process. They are only present in conventional petroleum oils because removing them would be impossible or excessively expensive.

When thermal or oxidative break down of petroleum oil occurs, it leaves engine components coated with varnish, deposits and sludge. In addition, the lubricant which is left is thick, hard to pump and maintains little heat transfer ability.

In addition, petroleum oils contain paraffins which cause dramatic oil thickening in cold temperatures. Even with the addition of pour point depressant additives, most petroleum oils will begin to thicken at temperatures 10 to 40 degrees warmer than synthetic oils.

As a result, petroleum lubricants will not readily circulate through your engine's oil system during cold weather. This may leave engine parts unprotected for minutes after startup. Obviously, significant wear can occur during this time frame.

Even when all conditions are perfect for conventional oils to do their job, they fall far short of synthetic oils. Part of the problem is that (because of their refined nature) petroleum oils are composed of molecules which vary greatly in size. As the oil flows through your vehicle's lubrication system, the small, light molecules tend to flow in the center of the oil stream while the large, heavy ones adhere to metal surfaces where they create a barrier against heat movement from the component to the oil stream. In effect, the large, heavy molecules work like a blanket around hot components.

There is also another effect of the non-uniformity of petroleum oil molecules which reduces their effectiveness. Uniformly smooth molecules slip over one another with relative ease. This is not the case with molecules of differing size.

Theoretically, it might be somewhat similar to putting one layer of marbles on top of another (if this could easily be done). If the marbles were all of the same size, they would move over one another fairly easily. However, if they were all of differing sizes, the result would be much less efficient.

In the case of petroleum oils this inefficiency leads, ironically, to added friction in the system (the very thing that lubricants are supposed to reduce). Hence, petroleum oils are only marginally capable of controlling heat in your engine. Considering that motor oil does nearly 50% of the cooling of your engine, that's not a good thing. But,

This being said, petroleum oils are “adequate” for the purpose of protecting your engine, if you don't mind a shorter vehicle lifespan, inconvenient oil changes, or decreased engine

performance. Under normal circumstances, most vehicles lubricated with petroleum oil should run satisfactorily for 100,000 to 150,000 miles without serious incidence.

If you like the hassle of changing your oil regularly, and you are only looking for marginal

performance for the next 100,000 miles or so, petroleum oils are definitely the way to go.

Assuming that you don't relish the idea of changing your oil every 2,000 miles or and are looking to keep your “pride and joy” in tip-top condition then these are the main areas where synthetic oils surpass their petroleum counterparts.

Oil drains can be extended

Vehicle life can be extended

Costly repairs can be reduced

Fuel mileage can be improved

Performance can be improved

oilman
25-01-05, 12:10 PM
Synthetic basestock molecules are pure and of uniform size. This is because synthetic basestocks are designed from the ground up with the sole purpose of protecting your engine. Nothing is added if it does not significantly contribute to the lubricating ability of the oil.

In addition, in top-quality synthetics, no component is added which might be contaminated with any substance that might lessen the lubricating qualities of the oil. In other words, manufacturers of these premium synthetics implement very strict quality control measures to insure no contamination.

Not only that, synthetic basestocks are designed so that the molecules are of uniform size and weight. In addition, synthetic basestock molecules are short-chain molecules which are much more stable than the long-chain molecules that petroleum basestocks are made of. This significantly adds to the lubricating qualities and stability of the oil.

EXTENDED OIL DRAINS

Stable Basestocks

Synthetic oils are designed from pure, uniform synthetic basestocks, they contain no contaminants or unstable molecules which are prone to thermal and oxidative break down.

Moreover, because of their uniform molecular structure, synthetic lubricants operate with less internal and external friction than petroleum oils which have the non-uniform molecular structure. The result is better heat control, and less heat means less stress to the lubricant.

Higher Percentage of Basestock

Synthetic oils contain a higher percentage of lubricant basestock than petroleum oils do.

This is because multi-viscosity oils need a great deal of pour point depressant and viscosity modifying additives in order to be sold as multi-viscosity oils.

Synthetic oils, require very little in the way of pour point depressants and viscosity

modifiers. Therefore, synthetic oils can contain a higher percentage of basestock, which actually does most of the lubricating anyway. More basestock leads to longer motor oil life.

Additives Used Up More Slowly

Petroleum basestocks are much more prone to oxidation than synthetic oils, oxidation inhibitors are needed in greater supply and are used up very quickly. Synthetic oils do oxidize, but at a much slower rate therefore, oxidation inhibiting additives are used up much more slowly.

Synthetic oils provide for better ring seal than petroleum oils do. This minimizes blow-by and reduces contamination by combustion by-products. As a result, corrosion inhibiting additives have less work to do and will last much longer than within a petroleum oil.

Excellent Heat Tolerance

Synthetics are simply more tolerant to extreme heat than petroleum oils are. When heat builds up within an engine, petroleum oils quickly begin to burn off. They volatize. In other words, the lighter molecules within petroleum oils turn to gas and what's left are the large petroleum oil molecules that are harder to pump.

Synthetics are resistant to this burn-off. They will tolerate much higher engine temperatures.

EXTENDED VEHICLE LIFE WITH FEWER REPAIRS

Heat Reduction

More often than not, vehicle life is determined by engine life. One of the major factors affecting engine life is component wear and/or failure, which is often the result of high temperature operation. The uniformly smooth molecular structure of synthetic oils gives them a much lower coefficient of friction (they slip more easily over one another causing less friction) than petroleum oils.

Less friction, of course, means less heat in the system. And, since heat is a major contributor to engine component wear and failure, synthetic oils significantly reduce these two detrimental effects.

In addition, because of their uniform molecular structure, synthetic oils do not cause the "blanket effect" which was mentioned earlier. Since each molecule in a synthetic oil is of uniform size, each is equally likely to touch a component surface at any given time, thus moving a certain amount of heat into the oil stream and away from the component. This makes synthetic oils far superior heat transfer agents than conventional petroleum oils.

Greater Film Strength

Petroleum motor oils have very low film strength in comparison to synthetics. The film strength of a lubricant refers to it's ability to maintain a film of lubricant between two objects when extreme pressure and heat are applied.

Synthetic oils will typically have a film strength of 500% to 1000% higher than petroleum oils of comparable viscosity. In fact, believe it or not, even though heavier weight oils typically have higher film strength than lighter weight oils, a 0w30 or 5w-40 weight synthetic oil will likely have higher film strength than a 15w40 or 20w50 petroleum oil.

Thus, even with a lighter weight oil, you can still maintain proper lubricity and reduce the chance of metal to metal contact when using a synthetic oil. Of course, that means that you can use oils that provide far better fuel efficiency and cold weather protection without sacrificing engine protection under high temperature, high load conditions. Obviously, this is a big plus, because you can greatly reduce both cold temperature start-up wear and high temperature/high load engine wear using the same low viscosity oil.

Engine Deposit Reduction

In discussing some of the pitfalls of petroleum oil use, engine cleanliness is certainly an issue. Petroleum oils tend to leave sludge, varnish and deposits behind after thermal and oxidative break down. They're better than they used to be, but it still occurs.

Deposit build-up leads to a significant reduction in engine performance and engine life as well as increasing the number of costly repairs that are necessary. Since synthetic oils have far superior thermal and oxidative stability than petroleum oils, they leave engines virtually varnish, deposit and sludge-free.

Better Cold Temperature Fluidity

Synthetic oils and other lubricants do not contain paraffins or other waxes which dramatically thicken petroleum oils during cold weather. As a result, they tend to flow much better during cold temperature starts and begin lubricating an engine almost immediately. This leads to significant engine wear reduction, and, therefore, longer engine life and fewer costly repairs.

oilman
25-01-05, 12:11 PM
IMPROVED FUEL MILEAGE AND PERFORMANCE

As indicated earlier, synthetic oils, because of their uniform molecular structure, are tremendous friction reducers. Less friction leads to increased fuel economy and improved engine performance.

Any energy released from the combustion process that would normally be lost to friction can now be transferred directly to the wheels, providing movement.

Vehicle acceleration becomes swifter and more powerful while using less fuel in the process.

The uniform molecular structure of synthetic oils has another performance enhancing benefit as well. In a petroleum oil, lighter molecules tend to boil off easily, leaving behind much heavier molecules which are difficult to pump. Certainly, the engine loses more energy pumping these heavy molecules than if it were pumping lighter ones.

Since synthetic oils have more uniform molecules, fewer of these molecules tend to boil off.

More importantly, when they do, the molecules which are left are of the same size and pumpability is not affected.

Cheers

Guy. :thumb:

chris m
25-01-05, 12:41 PM
Oilman,

As we are on the subject....

My (Good Ol' US) LS6 engine specifies use of "mobile 1" on the oil filler cap, with a spec of 5W-30, the Mobile 1 in this country is 0W-40.

This is sort of academic interest really, but why the difference?

oilman
25-01-05, 01:00 PM
Oilman,

As we are on the subject....

My (Good Ol' US) LS6 engine specifies use of "mobile 1" on the oil filler cap, with a spec of 5W-30, the Mobile 1 in this country is 0W-40.

This is sort of academic interest really, but why the difference?
The reason it says Mobil on the filler cap is probably marketing, oil companies pay a premium for car or engine manufacturers to recomend their brand of oil.

The Mobil 1 5w-30 is an american grade due to how hard engines have to work over there, over here we tend to use a 5w-40/0w-40 however if you wanted a fully synthetic 5w-30 there are a few around, Motul do some very high spec ones.

Hope this helps.

Cheers

Guy.

russj
25-01-05, 01:24 PM
Thanks for the technical explanation of what I have found in practice.
That explains to me why the RedLine fully synthetic does not gas off the same in a hot engine when driving it hard and I get virtually no oil usage in the same engine.

Russ

russj
25-01-05, 01:54 PM
Oilman,

The Redline I am using is 20/50.

Can you please explain what the this means?

Is this considered a thick oil?

Thanks

Russ

oilman
25-01-05, 02:04 PM
Oilman,

The Redline I am using is 20/50.

Can you please explain what the this means?

Is this considered a thick oil?

Thanks

Russ
Russ,

No problem.

The 20w-50 is a thick oil.

The first number with the w next to it is the viscosity of the oil when at cold crank temp, the lower the number the thinner it is 20w, 15w, 10, 5w, 0w. The other number is the viscosity of the oil when hot, the higher the number the thicker it is, so 30, 40, 50, 60

This may help some more.

A good oil must be quite low in viscosity even when it's cold so that it gets around the engine in a fraction of a second when you turn that key!



On the other hand it needs to protect engine components like piston rings at very high temperatures as the engine gets hot without evaporating or carbonising and it must maintain oil pressure.



Unmodified thin oils simply can't perfrom this balancing act. The answer is to use a mixture of thin oil and temperature-sensitive polymer which as the oil gets thinner with increasing temperature expands and effectively "fights back", keeping the viscosity at a level to hold oil pressure and film thickness on the bearings.



So, these polymers are added to a thin base, 0w,5w,10w etc at cold tempertaures they are "coiled up" and allow the oil to circulate very easily

but as the engine and therefore the oil warms up, the begin to "uncoil" into long chains keeping the oil more viscous.



It is impossible to make a good 5w-40 or 10w-40 using only mineral oil. The base oil is too thin and evaporates away at high temperatures found in powerful engines that are highly stressed, this is why synthetics are used to build up the oil to cope with the stresses of modern engines.



This is called a multigrade.

Cheers

Guy.

mr bidd
25-01-05, 02:13 PM
Hello Guy, you obviously know your stuff when it comes to oil. So to answer my original question at the beginning of this thread, which oil would you recommend in a newly rebuilt Rover V8 engine?

Thanks Chris

oilman
25-01-05, 02:18 PM
Hello Guy, you obviously know your stuff when it comes to oil. So to answer my original question at the beginning of this thread, which oil would you recommend in a newly rebuilt Rover V8 engine?

Thanks Chris
OK,

The RV8 does like the thicker oil, so keep it thick around the 15w-50 grade, 10w-50 to be ideal as that will give better cold start protection.

I am a synthetic man personally, so I would suggest the likes of a true PAO/Ester synthetic such as Motul, Silkolene, Redline or Mobil 1.

Cheers

Guy.

snakebite
25-01-05, 08:52 PM
Hi Guy

Reading your posts with much interest, I concur you certainly know your stuff. What advice for a chevy engine circa 1974 with about 2k on a complete re-build. :thumb:

oilman
25-01-05, 11:56 PM
I would use Silkolene PRO R 15w-50 fully synthetic.

http://www.opieoils.co.uk/TechSpecs/pro%20r%2015w-50%20-%204%20wheel.pdf

Cheers
Guy

osgood
26-01-05, 08:45 AM
Cant say much about that then Guy, good scientific answers in-fact I am so impressed I may give synthetic a go but obviously after I have run my new unit in.


Right couple of questions of my own for you, I take it mineral oil does not mix with Synthetic too well, I don't really want the flush the engine out at this stage (500 mile only & one oil and filter change so far) being a new unit and costing a great deal of wedge, although at this stage the inside is cleaner than the out so no bits to dislodge.

Could I drain sump, change filter etc, and replace with semi synthetic and then move onto fully synthetic on the next change?

Also what is your views on vegetable oil such as the modern equivalent of Castrol R?

Thanks Eric.:)

oilman
26-01-05, 10:48 AM
Cant say much about that then Guy, good scientific answers in-fact I am so impressed I may give synthetic a go but obviously after I have run my new unit in.


Right couple of questions of my own for you, I take it mineral oil does not mix with Synthetic too well, I don't really want the flush the engine out at this stage (500 mile only & one oil and filter change so far) being a new unit and costing a great deal of wedge, although at this stage the inside is cleaner than the out so no bits to dislodge.

Could I drain sump, change filter etc, and replace with semi synthetic and then move onto fully synthetic on the next change?

Also what is your views on vegetable oil such as the modern equivalent of Castrol R?

Thanks Eric.:)
Eric,

Do give synthetics a go.

We tend not to recomend mixing any form of oil as it can affect the different addative pack within each oil.

If you are running in the engine, run in on good rich mineral oil for around 1000 miles and you can switch straight to a synthetic.

To do this you will not need a flush, just warm the engine and leave to drain. This will get most of the old oil out, what is left will be taken care of by the detergents in the synthetic going in.

Castrol R is still going strong, however I stock the Silolene Castor oil and what a wonderfull smell:D However they are mono grades and need great care when starting the engine, so you would have to let the engine run on tickover for some time to warm up the oil or a method of pre-heating the oil, once up to temp though they are extremely good at lubricating but they don also break down very quickly and need changing at very regular intervals.

Hope this helps.

Cheers

Guy.

grandadboats
26-01-05, 11:22 AM
I asked this before, but got no reply, so I'll try again.
Has anyone used Activ8 additive? It is a friction reducer I saw demoed at exeter. Obviously not for new/rebuilt engines, but mine (v12) isn't. Should I use it?
Tony

oilman
26-01-05, 01:00 PM
I asked this before, but got no reply, so I'll try again.
Has anyone used Activ8 additive? It is a friction reducer I saw demoed at exeter. Obviously not for new/rebuilt engines, but mine (v12) isn't. Should I use it?
TonyIn my opinion, no.

It is up to you but have a read of the following.

A number of ‘add-on’ additives intended to improve the performance of commercially available automotive lubricants have been marketed in recent years, under such names as ‘Xxtralube ZX-1’, ‘Metol FX-1’, ‘PPL Anti-Friction’ and ‘Activ-8’.All such products share the following characteristics with ‘X-1R Friction Eliminator’:-



1)They all contain chlorinated paraffin ‘exteme pressure’(EP) compounds first used in the 1930s in heavily-loaded industrial gearboxes, and in some automotive transmission applications, mainly hypoid gears.



2)They all corrode copper-based alloys at moderate temperatures, easily exceeded in all engine, and most transmission applications.This problem was recognised in the 1930s, and chlorinated compounds were never used in transmissions with bronze bearings or gears. No responsible manufacturer ever suggested using them in engines where their increasing activity at high temperatures could lead to piston ring corrosion and bore glazing. (For the same reason, modern ‘hypoid’ additives are not used in engines, even though they are much safer than any chlorinated additive.)



3)X-1R Friction Eliminator and its clones are based upon very outdated technology, which was abandoned by responsible lubricant manufacturers for automotive transmission uses in the 1950s. Chlorinated compounds still find applications in metal working, but their use is on the decline because of health and safety considerations.



4)When burnt, chlorinated paraffins produce corrosive hydrochloric acid, and organo-chlorine compounds including the highly poisonous phosgene gas. Apart from these corrosion and health hazards, with petrol engines the deactivation of exhaust catalysts is also a problem.



5)Unfortunately, these additives give spectacular results in simple EP test machines such as the ‘Falex’. As a marketing ploy, a demonstration of this type looks impressive to those not aquainted with the above facts. Also attractive is the low cost of chlorinated compounds, allowing profits of several thousand percent to be made.



I know I wouldnt.

Cheers

Guy:thumb:

grandadboats
26-01-05, 01:08 PM
Many thanks for that. It certainly is not inexpensive at retail!

Don't think I'll botherCheers
Tony

chiffer
26-01-05, 01:18 PM
I have a Ford 351windsor engine, completely new 1998, not re-built, and was told by the person who built the car not to use synthetic oil and use only normal Castrol GTX. What is your opinion?

Regards

snakebite
26-01-05, 06:06 PM
I would use Silkolene PRO R 15w-50 fully synthetic.

http://www.opieoils.co.uk/TechSpecs/pro%20r%2015w-50%20-%204%20wheel.pdf

Cheers
Guy
Hi Guy

Thanks very much for your reply, just one small query that hopefully you can dispell. I have heard that because the cams are not pressure fed but rely on splash, that to quote David Vizzard, you will wear the cam out quicker using synthetic oil, :-( why, I havn't got a clue. What's the prognosis.

oilman
03-02-05, 09:15 AM
I put your question to John Rowland (Chief R&D Chemist for Silkolene) and here was his reply - hope this answers you.

Quote:

Guy.

Sigh….what sort of synthetic wears the cams out? David Vizard (one ‘z’) is THE ace man on gas-flow in cylinder heads; his ‘Tuning The A-Series Engine’ is brilliant; but oils are not his strong suit. A USA fuel economy 5W/30 based on PAO or hydrocracked probably would do as he says, but a shear-stable European ester-based synthetic would be better than any mineral grade. Pro-R 15W/50 is just the thing for large American V-8s.

John Rowland

Unquote:

Cheers
Guy

mikey
03-02-05, 01:27 PM
I think you are probably in the right. Howerver I wanted to use synthetic and rang Crower cams about their disclaimer. They do not state that synthetic oil is a no no just that it is not recommended and should NOT BE USED DURING BEAK IN. Edelbrock and competition cams would appear to have the same policy on the US stuff.

The guy at Crower said that there was a very good chance that the cam and possibly lifters would be screwed during break in - something to do with the oil adhering to the lobes, nothing to do with viscosity. Their advice was at best to run in with a mineral and if high lift an additive and then if required change. However Crower warranty is voided as they believe the protection from synthetic is not as good as a quality mineral and that the benefits are more about running higher miles with less breakdown and less susceptibility to temperature - ie everyday motoring with cluless motorists who dont regularly service.

Dont know if the same is true of comp cams or edelbrock, but the same disclaimer is stated on their product cards.

I think its a matter of is there some substance in what they say or is it the old dynasaur bit about reluctance to change. Unfortunately I could not afford the gamble of making the wrong decision as the cam I run is as radical as you get on a street/strip car and wasn,t cheap.

It would be great if somebody like you would discuss this with the manufacturers as I would welcome the free HP free up with synthetic but am not yet prepared to ignore the diclaimer.

Cheers

Mike.

oilman
03-02-05, 02:25 PM
I would also advise to run-in on mineral oil then change once run-in.

Synthetics merely prolong the run-in period.

Cheers
Guy