Is it good to change manual transmission fluid?

[RawToast]

So I've bought Royal Purple Synchromax transmission fluid but I just heard from two friend's of mine that it is not beneficial to change manual transmission fluid in E30's. No idea why but they said something about the age of the car / oil.. Not quite sure. Opinions?

As a side note, what oil should I use for my differential?

[RoadWarrior]

I just changed mine while my swap was out. I used Redline MTL 90. Its night and day. Smoother gear changes all around the transmission feels better. Change it and call it a day.


-seth

[UserError]

BMW service requirements state that you should change your transmission and diff oil every 30k miles or so, as part of an inspection 2 service. As for diff oil, your best bet would be 80W90 GL-5 for regular differentials, and 85W140 GL-5 with LSD additive, if you've got a limited slip unit.

[reelizmpro]

Oh yeah, nothing beats used vintage gear oil. The older the better.

[Quadrajet]

Lol!

[TobyB]

MTL every 30k. Give Plebian Purple to friends for entertainment.

t

[reelizmpro]

MTL every 30k. Give Plebian Purple to friends for entertainment.

t

I go extended on synthetic gear oil ...50-60k. It comes out almost as good as it went in. Won't hurt to change it at the factory spec though.

[MR 325]

Definitely a good idea to change trans/diff fluids.

I use generic Valvoline or Castrol 75w90. No synthetic and nothing fancy.

[ieatpeople]

OP, your "friends" are sort of right, just not about a manual trans.

i've always heard that if you have a high mileage automatic trans that you should not change the fluid, just the filter. i don't agree with that, but alot of people do.

for a manual trans, changing the fluid is good for it. and it makes it nicer to drive.

[entrepreneuR]

Since we're are the topic...how many quarts do i need for a complete trans flush? (5 spd)

[Holland]

It's bad to FLUSH high mileage auto transmissions after not being serviced ever. Drain and fills are ok.

[MR 325]

Since we're are the topic...how many quarts do i need for a complete trans flush? (5 spd)

2 for the trans, 2 for the diff. You'll have extra.

[entrepreneuR]

2 for the trans, 2 for the diff. You'll have extra.

Gotcha..thanks!

[drumad]

Didn't see it mentioned yet but check what sticker your tranny has. It may take ATF also.

[MR 325]

Didn't see it mentioned yet but check what sticker your tranny has. It may take ATF also.

That's true. Some Etas and M42 cars take ATF in the trans.