What is proper oil for M40 transmission??

[markus_74]

Dear, Bimmers

I had problem to choice what oil I should use for my getrag?

I use ATF oil at this moment but the sound of metal to metal knocking is very loud when the car is stop with engine still running.

I have tried use 80 grade oil and the knocking sound is reduced a lot but the car will lazy to move because the oil is too thick.

What is proper oil to reduce the knocking sound but not making the car move lazy?

Need suggestion
markus

[Heyho]

Well, you've tried both of the approved grades of oil, so why not try a 50/50 mix?

[Brianmoooore]

Either is correct, but it's a Catch 22 situation. Poor shifting or noisy layshaft bearings.
Which do you dislike the least?

[markus_74]

Either is correct, but it's a Catch 22 situation. Poor shifting or noisy layshaft bearings.
Which do you dislike the least?

I think the shifting is still easy when the engine is hot , but the car feel sluggish, I feel that the oil in the transmission reduced the engine power.