Manual trans fluid and diff fluid selection

Gregory_tolson · Aug 25, 2020

Hey z4 owners, i have the 6 speed manual GS6-37BZ/DZ transmission in my '03 M54B30 z4 (car has 83k miles). I was wondering which product i should purchase for the transmission fluid and diff fluid:

1.) Manual trans fluid - should i purchase Redline's 75w80 (pn 50204)? Or should i purchase Febi's 75w80 (pn 40580)? Both i found on fcp euros website

2.) Diff fluid - should i purchase Liqui moly's 75w90 (pn LM2048) fully synthetic gear oil? Or should i purchase Redline's 75w90 (pn 57904) GL-5 gear oil? Both also on fcp euro's site.

Would like to hear testimonial reviews. Not sure why Febi has the OEM marking on fcp euros site while redlines MTL does not.

Gregory_tolson · Sep 1, 2020

Any thoughts?

rsutoratosu · Sep 17, 2020

Fk I like to know too on #2, I use redline 75w90 before, and saw liqui molly on fcp too. Anyone ?

Gregory_tolson · Sep 17, 2020

Is the redline suitable?

rsutoratosu · Sep 17, 2020

Yes, redline is fine but because I threw away my bottle, theres GL4 & GL5, gl5 will eat brass (from all the google sites), I dont think our rear diff has brass in it.. I can't remember what I order 2-3 years ago..

The difference between GL-4 and GL-5 explained - GL5 will get bronze and copper. I dont think that affects us but no one can confirm for me..

Muskrat14 · Sep 19, 2020

Check out ECS Tuning website. You can load in ur model then search. They will list compatible gear lube. They everything from BMW gear oil to Redline and others. Looks like GL4 and GL4+ keeps popping up.

Sent from my iPhone using Tapatalk

rsutoratosu · Sep 25, 2020

Yeah i was pretty sure I used gl4 before. not going to risk using gl5 and get issues.

rsutoratosu · Sep 27, 2020

So while cleaning out the shed over the weekend.. I found my left over redline.. apparently I been using gl5 for the past 10 years... lol. No issues with GL5 (for me)

Manual trans fluid and diff fluid selection

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