Manual Transmission Lubrication

Hey everyone, I'm planning on changing the transmission oil in my '90 E34 M20. I have read a lot of conflicting opinions, it seems no one agrees on what to put in the gearbox.. So what are your opinions/experiences? ATF, diff oil, motor oil?

Since I have an automatic, I haven't looked it up, but I would use the owner's manual as my primary resource and the Bently manual as the secondary resource.

I have had personal experience with both Redline and Royal Purple.

RP smoothed out the shifting in the E39, after the Redline made it nearly impossible to shift.

WhenI got the E34, I just went with what was working for me in the past.
No problems.

In all fairness to RL, people in the 39 forum use it to great satisfaction, so maybe my 540 is allergic.

Oh, ATF is what it calls for.

hb

Originally Posted by haolibird

I have had personal experience with both Redline and Royal Purple.

RP smoothed out the shifting in the E39, after the Redline made it nearly impossible to shift.

WhenI got the E34, I just went with what was working for me in the past.
No problems.

In all fairness to RL, people in the 39 forum use it to great satisfaction, so maybe my 540 is allergic.

Oh, ATF is what it calls for.

hb

I just looked at Bentley (just to learn) and found it to be quite vague. Your advice seems to be based on much experience.

OP, I would take HB's advice were I in your position

What does the hand book say? Have you tried the Castrol (or other manufacturer) sites?

BMR LVR,

Thanks for the props.

If you crawl under the car, there is (should be) a tag specifying fluid. (Mine does).
We have the same model year.
I don't know if they put a different trans in the 525 than the 535.
Wiki would tell the tale, as well.

Have you looked?

T

Ignore the transmission model. Dex3 is supposed to be dangerous to my tranny according to bentley but i have been using it for 3 years with no problems. Use any type of semi or fully synthetic transmission oil. Only the big boys have it and you cant go wrong. If unsure just use zf lifeguard. However this is very pricey, but you can basically double your oil change interval over dino oil.

Or just follow haolibird's suggestions. Royal Purple seems to be the aftermarket brand with the best track record.