what oil in an old V8

[pevans]

Just a quick check to see what oil people are running in their older American V8's ? Mine is a 1970 Ford so I just bought some classic 20-50 oil from Halfords as I dont think all this modern stuff will work well on an old engine ?

[AKBaz]

Valvoline 20W 50 for me. Has all the right stuff for these engines.

Baz

[jon1d]

Another one for Valvoline VR1 20w 50.

[nealgs]

Mineral oil, 20w50 with Zinc additives - VR1 Racing, Millers Classic, Lucas Hotrod

[BomberG]

Valvoline VR1, mineral oil with zinc, 20w50 (in 350 Chevy)

[Bigblock]

20/50 for me, big block ford.

[TINKA]

Valvoline VR1, mineral oil with zinc, 20w50 (in 351W)

[conrod]

Magnatec 10w40 semi-synthetic in SBC stroker.

I used to use VR1, but I was advised by Mike Huddart that 20w50 is too viscous and doesn't lubricate well enough from cold, and he recommended using a 10w40 or 15w40 semi synthetic oil. As for zinc/ZDDP content, Valvoline state that VR1 racing oil contains 0.13 per cent ZDDP, which is 1300 ppm (parts per milliion). After sending an email to Castrol's technical department regarding the ZDDP content of their oils, I received the following interesting reply:

"Many of the Castrol products (from Heavy duty truck, Agri and Automotive passenger car oils) carry around 900 - 1050 ppm zinc which we feel is perfectly suitable for all engine types including the old
flat tappet ones.

Castrol products to consider for your Chevrolet would be Castrol GTX 15W-40 / 10W-40 - zinc levels are around 980 ppm typical and this is a good basic oil suitable for older engines if you have a preference for a
basic oil, or the Magnatec 10W-40 would offer enhanced performance and protection of the Magnatec anti-wear additive as well as similar levels of zinc in GTX, and be an ideal all round oil assuming the car engine
is in good condition and doesn't use oil in its current state. Both of these are part synthetic oils.

Bear in mind that zinc is a largely passive additive and is only needed/activated when there is a break in the oil film and metal to metal contact occurs. In this instance the anti-wear additives react to the
heat generated and form a protective surface to prevent wear. The amount of zinc in the formulation doesn't mean better protection. If a good quality oil is used such as Castrol Magnatec or GTX, then in theory
there should be little need for the anti-wear additive (or certainly less need) as the oil should always provide a good lubricating film between the moving surfaces in the engine. Having an oil with 1500ppm
zinc is no real benefit for anti-wear than one with 1000ppm zinc in this case. In fact too much zinc (above 1500ppm if my memory serves) has been shown to cause issues with pitting so you can have too much of a
good thing! The complete package of base oils and additives is more important than just the zinc levels alone. We wouldn't condone using aftermarket additives either as these can be detrimental to the careful
balance of the engine oil formulation that has been carefully blended to provide the right performance and protection as it is.

There was a suggestion that modern petrol oils from API SM / ILSAC GF-4 had to carry less zinc and phosphorous because of the effect on the catalytic convertor and that using a diesel engine oil was better - but
looking at the Castrol range of products, they still fall into broadly the same levels of around 900 - 1050 ppm so no real benefit there - I think the issue is maybe more in the USA where the latest API SN oils
can carry lower levels of around 600 - 800 ppm - but these formulations are not used in the UK, and as the oil drain intervals in the USA are a lot lower, they can also probably get away with less anyway, especially
in later engines.

Magnatec 10W-40 would certainly be my preferred Castrol candidate if the engine is in a good state of tune and wear - if its worn and using oil, GTX 15W-40 may be a cheaper solution."

I have been using Magnatec since my engine rebuild five years ago. I average 4000 miles a year, and the oil level rarely needs topping up.

[nealgs]

Following up on Alans comment above - since my rebuild in early 2017, engine builder moved to using 10w40 mineral instead, so using Lucas Hotrod now rather than VR1 383 stroker running roller rockers and cam.

Gary

[ChrisP]

I use Morris' HD3 20/50 and swear by it. It's suitable for petrol and diesel engines. A good oil for engines of this era. I raced my 427 for years with this and it did really well. It was also used by a lot of my racing pals. Dead right for a 1970 V8 in my view! As always, everyone will have their favourites........Morris' also have a good technical team if you want to talk options through.
https://www.morrislubricantsonline.c...d3-20w-50.html