I am considering changing the trans oil in my M46 trans that was rebuilt about 3000 miles back and was considering Redline MTL in place of Type F ATF because the car is driven in winter monvhs only at temps ranging down to -40F ( or C for that matter!). I checked the archives and found one mention that this was an OK product. Any comments or experiences welcomed.

I put Redline's MTL in my 83 244 with M46/OD about 5 yrs ago (when I was living in Calgary)- it's still in there and I now live in Southern Calif. Instant improvement in shift smoothness and effort. When the really cold weather came, shift effort was a lot LESS than with ATF. My final observation was that after driving at highway speeds in warm weather, the OD was less prone to shuddering and trying to disengage when the speed dropped down to about 70km/h (42mph).

Here's what I concluded: the MTL does indeed have better frictional characteristics for the synchronizers; its viscosity seems to be less temperature sensitive - it doesn't get as thick at low temps, or as thin at high temps, as ATF. Plus if you believe the Redline literature, it has superior anti-wear additives for manual gearboxes compared to ATF. I know the OD needs a seal kit, but the MTL has bought me a lot of time on that. Make sure you get their lighter grade MTL, they make another heavier grade not suitable for the M46. I also put their rear axle gear oil (70W90?? - can't remember) in and observed less "stiffness" of the car rolling out of the driveway after parking all night in -30C.

Another choice is Redline "racing" ATF which is type "F". I've used both MTL and racing ATF in my M-46, but only at coastal California temps. Both make up for leaky seals, neither leads to slippage.

I did have a problem with Redline MTL in my M46 (1986 744T). After a bit of communication with Duane, we decided that the sprague clutch was not engaging well when the transmission was cold. Felt like clutch slippage between gears. A change, on his advice, back to type F cured the problem. I know others have run MTL successfully, not sure what is different about mine. I used Castrol type F, but now that I know it works, I would use synthetic next time.

Yeah, if I was in Calgary, I'd use synthetic ATF, too. I don't actually have to deal with "cold". "Hot" I can tell you about.

Redline MTL is a good product, but why not use synthetic Type F, especially at those very cold temps? I'm not so worried about the cone clutch slipping with the MTL (although that should be a concern) I worry about the high pressure pumpability.

Synthetic Type F= Amsoil Supershift, product code: ART.
--
www.fidalgo.net/~brook4