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Changing diff fluid. Oem or not?

7K views 35 replies 20 participants last post by  KashM3 
#1 ·
Balanced my tires at the shop today and notices a couple of drops from the diff drain plug. I'm planning on changing the diff fluid and was wonder if oem fluid is worth the premium price or is there something else that you guys have used in your car. Turner has both oem and another brand for sale. Any feedback is greatly appreciated. Sponsor welcome to reply with some prices and products.
 
#3 ·
non-m open's use 75-90 i use that weight with redline and have no complaints always feels good putting new fluid in. don't go oem fluid its pointless and has no benefit .. it comes down to if you want to put in redline or RP i put redline in every place i could. you should try out putting RP in the diff and redline in the tranny I'm sure you will be happy any which way
 
#5 ·
don't go oem fluid its pointless and has no benefit ..
Please don't make blanket statements. As stated, non-M open diffs and M LSD are different and need different fluid. The FM Booster was added to reduce noise/diff whine. Many M3 owners switched to Redline or RP and noticed add'l whine after few thousand miles, fix = OEM fluid with FM Booster.

OP, your car will work fine with non-OEM fluid but I suggest you use it in case you find non-OEM fluids making un-wanted noise. Changing it once with more $ fluid is still cheaper than changing it twice with non-OEM and then OEM.
 
#19 ·
Probably would have, but not willing to pay that much for fluid. I did many forum searches and also past experience with RP products. I Machine and build custom racing engines for a living. I have used RP products in the past. The concensus on the forums was to either use RP or RL oil in the diff and tranny....NOT factory stuff as some have suggested in this thread. I know how to use the search function. :)
 
#25 ·
if I had an M3, royal purple products wouldn't come anywhere near it..

really - how often do you have to change the diff fluid? maybe 3-4 times over the life of the car? I feel the same way with coolant. Yeah, it's an extra $20 for the BMW stuff - but that's spread out over two years. I've seen the damage from using cheap fluids and it's just not worth it. BMW stuff is formulated exactly for your car, you don't have to guess or hope it will work.
 
#26 ·
FWIW, I have 391 gears recently installed, they used non OEM diff fluid, and it made noise, added the OEM with FM booster, no more noise, AT ALL! I'm telling you guys, the stuff is unmatched!
 
#31 ·
OEM! I used a few years ago and its still good. The BMW limited slip diff is very picky and likes the FM booster...and no you can't by the booster by itself. If you swap the locker, you can use different fluid.
 
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