Fluids

[Nick_e30]

I know there's a million threads on this but I see different answers on each one. I have an 89 325 lsd and manual trans which oil should I use in each? Is 75w90 in the diff and 75w80 in the trans ok?

[dnguyen1963]

Go with the Bentley recommendation when in doubt.

[ELVA164]

Those are both fine. BMW now recommends 75w-140 for the diff, to reduce noise and increase life, but the 75w-90 is fine. You could also use 75w-90 in the gearbox (a la MT-90) without any issues. People have found smoother shifting going both ways. I currently use redline MTL 75w-80 in the gearbox and redline 75w-140 LSD oil in my diff.

[estoguy]

That's interesting on the diff oil... going to look into a 75w140... but I wonder how that would be up here in the cold???

Right now I use Redline MT-90 in the tranny and the 75w90NS in the diff.

[jeffnhiscars]

75-140 is too heavy for a year round gear oil In Canada so I'd stick w 75-90.

There are 3 different fluid specs for a manual. Different stickers, no sticker....not completely sure but one uses atf, I used mtl in mine etc etc.

[ELVA164]

Again it's all a matter of personal preference, but I'd read a post from someone involved with the G260 that the sticker/type of fluid didn't have any real bearing on what HAD to be used. My gearbox is "supposed" to use MT90; I used it for two years with no issues, and now I've used MTL for two years with no issues. Gearbox shifts great and makes no noise. YMMV

[estoguy]

Again it's all a matter of personal preference, but I'd read a post from someone involved with the G260 that the sticker/type of fluid didn't have any real bearing on what HAD to be used. My gearbox is "supposed" to use MT90; I used it for two years with no issues, and now I've used MTL for two years with no issues. Gearbox shifts great and makes no noise. YMMV

Thanks Jeff... I was thinking that it would be too thick up here.

Elva is right... the labels indicated what the factory fill was - there were two types of oil and ATF used, depending on whether there was no label, a green one or an orange/red one. If you completely drain the tranny, you can refill with whatever.

I've been running MT-90 for 3 years in mine, no problems, gearbox shifts great.

When I did my diff seals while doing my rear subframe refresh, honestly, the oil looked new. No debris or anything. Redline is expensive, but it hasn't done me wrong.