title says it all, anyone know the correct weight for the final drive unit on the 97' e39 540i? running 75w90 mobile 1 synth now but i've heard that this is not the correct fluid, think someone said its supposed to be 74w140 iirc??

cmon guys, nobody knows the correct fluid for the 540? what are you gys running then? i searched everywhere and cant find any info.

I believe it is 75W90. But I could be wrong. The trouble is many of us have not dived into this because of the "lifetime" fluid that is in there. Anyone have the definative answer? I'd like to know too.

imo, anyonw who cares about their car would never leave any fluid in it for the life of the car, thats crazy. i actually just replaced the m1 75w90 with the bmw spec final drive fluid, though i will not be leaving it in there for the life of the car! lol.

I put Royal Purple Max Gear 75W90 in my final drive a couple of weeks ago. If it blows up, it blows up,,,,,, Has not blown up yet.

then its time for a lsd:devillook

How about pre stated Mobile plus the additive agent.......? I have the same guessing issue going on.....I can't find the answer for SHIT.....and I've searched everywhere. Some say this, some say that. My book doesn't even acknowledge having a differential.....I'm just gonna put some Bee Honey with sugar in there and see if it works. You ever try to pour that stuff.....It's like 90 W190.....

are yall talking about differential fluid ?

I'm running royal purple gear oil. I believe it's 75w90.

i just drained out the m1 75w90 and filled it with the oe bmw diff fluid, least i know its the right stuff for the car. damn owners manual only says bmw hypoid gear oil, rather ambigious as to the weight.

Where did you get the OE fluid nightkrawler? I thought that stuff only came in 55 gallon drums.

bear in mind i work for a bmw dealership so i get some perks, but you can go to a service dept at a bmw dealer and tell them you want to buy some diff fluid and they will sell it to you, bring something to put it in though, lol.

that "lifetime" tranny/diff fluid is complete BS in my book. Im sorry but there isnt a company on this earth that can prevent an oil based fluid from breaking down over time.

I bought my current 540i in january with a really notchy transmission. i couldnt get it to go into 3rd gear the 1st time so i drained that crap out of there, put in Pennzoil syncromesh fluid and my tranny shifts as good as new now. It was the "lifetime" tranny fluid that sucked.

I need to replace my diff oil as well.

how much is the diff oil ? and what weight does bmw sell ?