Rover LT77 gearbox oil

[chesterak]

The standard oil, I believe, is AF/Dextron or similar. Does anyone have experience of using alternative gb oils, maybe even semi/full synthetic? I'm a bit concerned that the hp/torque from a mildly tuned 4.6L may be too much for the standard oil.
stan

[russell_ram]

Stan,

The only reason ATF is specified for LT77 is that 'normal' customers seem to have great difficulty in engaging 1st and 2nd gear when the box is cold. The thinner ATF causing less drag than EP gear oils of old. The High/Extreme Pressure qualities of ATF are obviously not as good as those of a more conventional gear oil. For the latest R380 gearboxes in Discovery, which is basically the same as an LT77, Land Rover specifies Texaco MTF 94, which I believe is a 75/90 semi-synthetic. If I was you, I would change to this or a similar 75/90 s/s gear oil (ie valvoline). You may find syncro operation is a bit slower when the box is cold, but will improve as the oil gets hot - live with it and be confident in the fact your box will last longer.

I have put this in a number of LT77's and no one has complained and use valvoline in my 380.
Russ

[StuartH]

Russell,
is this considerably thicker than atf? if so it may not be a good idea - the chap who rebuilt my LT77 gearbox (CTS in Luton) reckoned that denser oils are not a good idea because the woosey plastic oil pump in the box cannot pump them, it just cavitates the oil or breaks.

Stuart

[russell_ram]

Stuart,

Of course it's more viscous than ATF, thats the whole point! The pump hasn't changed between LT77 and R380, and it's Land Rover that specify MTF94, not me. Think if you go back far enough (P5 - P6) you will find that they also specify 'proper' gear oil for four speed Rover box. As I say, we only specified ATF, particularly for 4x4 applications of the LT77, to make cold shifts easier. I don't know of any concern over pump cavitation/pump breakage.

Russ

[chesterak]

Russ,
Thanks for your reply....I too drive a Discovery with an R380 box. I have been fortunate (or unfortunate, depending on how you look at it!) to have had various Discoverys with the LT77 box, the modified LT77 pile of crap (4 boxes in 3 months)they fitted just before the R380, upto the current model. I had considered using the oil you suggest but I don't have sufficient knowledge on the effect of the increased viscosity on synchro operation. From you experience there doesn't seem to be any problems so I shall use the "proper" oil.
stan