Gear oil change ‘93 Griff with Rover ‘box

[bergxu]

Hi lads,

Would like to do a gear oil change on my ‘93 Griff 500 which I think (?) has the Rover LT77 gearbox (reverse is up and to the left). Saw some talk about them having ATF in from new then eventually folks were using synthetic engine oil in them. Was wondering what the collective here are using?

There’s nothing wrong with how my box performs, hot or cold, but figured not knowing when the oil was last done, might like to freshen it up.

I’m in the US, so some of the various Castrol products aren’t available here (SMX, for example), but I’m a big fan of Redline oil products (not sure if they have a presence in the UK or not).

Thanks as always, appreciate the wisdom!

[blitzracing]

Personally is stick to ATF. The syncro rings are not good at cutting through higher viscosity oils be it mineral or synthetic so you get a notchy and slow gear shift especially when cold. You get the odd story about ATF causing bearing failure on the LT77 but I would not consider this a problem on something like a TVR as most dont do massive mileages.

[bergxu]

Thanks blitz, so is Dexron III suitable then?

[Belle427]

I've just spent days reading about this and in the end went for the Redline mtl.
Atf was never designed to be anywhere near this gearbox, it was changed to Atf to overcome cold weather gear selection issues.
Some people may recommend an oil called difflock to you which is supposed to be the bees knees but from what I've read it's either amsoil mtf or redline mtl re bottled.

[spitfire4v8]

bergxu said:

Hi lads,

There’s nothing wrong with how my box performs, hot or cold, but figured not knowing when the oil was last done, might like to freshen it up.

I've no particular like or dislike for any of the oils mentioned .. I've happily used atf in these ever since the dealership days .. but one thing I would say is that regular oil changes are a must on the lt77. They have an internal pump which doesn't enjoy swarf running through it, so changing the oil often is a good thing whatever oil you actually end up using.

[bergxu]

Thanks for the additional replies gents. Yes, I had figured on using Redline MT-90 or MTL but I’m also fine to use ATF if that’s what I’d apex’s. I’ve no idea what’s in it now although I reckon I could ring up Dan Taylor over there in the UK and ask him what he used prior as he’s the one who maintained the car prior to my ownership. Or, could always drop the drain plug and see if the oil that comes out is brown or red… I just don’t want to mix gear lube and ATF, obviously.

[Belle427]

The Transmission rebuilders who have experience with the Lt77 in this country specify Atf to be fair as that's what has been recommended for years.
Some people chose to try an Mtf94 with good results, which I believe is a 75/80 viscosity.
It's like the great Rover V8 oil debate all over again!