Yabo

My transmission:

S2 LSD transmission with between 100 and 150k miles.
Slight grind going into second every once in a while on a cold morning.

Cost no object, what is going to be the best transmission oil to use?

I've done a search but wanted to ask in my specific case with the LSD and maybe there is a new product out there? I think I've used redline in the past.

Thanks for any help.

jstand22

Swepco 201

tk's944

I say Royal Purple. Solved my whine and 2nd gear grind in both of my 944s.

m73m95

Redline MT-90 is fantastic stuff.

I guess any of the good synthetics mentioned above would work just as well though. The redline is like nothing I've ever felt though. I can shift with one finger, and it just falls into gear....up or down.

Dmitry S.

+1.

Weston

Redline has done amazing things for me in my last track car, and I know people who report the same on 944 race cars (using MT-90)... My race car will have fresh Mobil 1 75w90 for it's next race, only because all the Redline distributors were closed when I went to buy gear oil today. I'd expect similar results, but we'll see how it goes...

FRporscheman

Not mobil 1. Mobil 1 is magic in 993/968 trannies though.

There have been countless discussions on this. Don't forget you can also search the turbo forum. People always take sides but the big names that get thrown around are swepco 201, redline mt-90, and amsoil 75w-90. For LSD, I'm sure each brand has a different version with friction modifiers, so watch out for that.

Yabo

Most of the threads aren't LSD specific.. are there any additives I should add for the LSD?

Thanks for the help all.

m73m95

all the synthetics should have the LSD additive in them already...unless they say they don't

Dmitry S.

Fluid that complies with GL5 standards should have the friction modifier for LSD.

wesmc3

Ditto. They are all great oils but redline will go further towards ending crunchy shifts.

Lizard944

1+ (or is it 5+ at this point?)

Redline MT-90 took all of the "notchy" shifting away. I previously used Swepco 201, but apparently, it's actually too slippery for some synchros. Always had an arm-wrestling match to get into second gear, esp. on cold days. Totally eliminated with the MT-90.

FRporscheman

I always get confused when I hear all the stories about Redline being so great, because I tried it in my 944 and it totally sucked, big time. Then I realized I had used 75w-90 ns, instead of mt-90, so be sure not to make that mistake.

I think though that I read somewhere the redline oil to use in an LSD is 75w-90 (not 75w-90 ns).

Yabo

SO, is MT90 or 75w-90 redline the one to use with LSD, or are they the same thing?

ArcticSteve

MT90 is sold primarily as a "manual transmission oil" that also can be used in transaxles with or without LSD. It's GL4 rated.

75W90 is sold primarily as a "gear oil" that also can be used in transaxles with or without LSD. It's GL5 rated.

75W90NS is sold primarily as a "gear oil" that also can be used in transaxles without LSD. It's GL5 rated.