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      03-03-2013, 01:27 AM   #7
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Drives: M5
Join Date: Aug 2007
Location: Brooklyn, NY

iTrader: (4)

Originally Posted by jjw2331 View Post
My dealer puts in FM booster diff oil regardless of noise. I had it in my diff after my 1200 mile service, again after a seal was replaced, and again after I got a replacement diff for a strange clunk that was not normal. Never did I complain about a grind, but I still got the FM booster fluid.

I asked my dealer for bottles of diff oil to change my own fluid last year. They gave me three bottles of 75w-140 diff fluid with FM booster. I know castrol saf-xj (now known as castrol syntrax limited slip) is the older fluid or what comes in our cars when brand new. So I asked for it and the parts guy said FM booster is only fluid we use on M differentials. I guess its the new standard fluid. But thats just from my experience.
Thanks for that I appreciate it. Either way im gonna make sure that's what they use in my diff for my upcoming service!

Originally Posted by Vic311 View Post
Originally Posted by Fen335i View Post
I used the OEM diff fluid w/FM booster as well on my last change. My goodness it's expensive...I might try an aftermarket high-end fluid next time. The OEM stuff is highway robbery...kind of like the 10-60 TWS oil! At least now Redline is making 10-60 now that is slightly cheaper.

Yea im gonna use the OEM stuff on this service aswell. I like to stick with the oem stuff. Just needed clearing up on what exactly and if the FM booster is the standard now. Thanks.
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