Diff fluid???

[E92_Blake]

I daily my 08 M3 but it also hits about 1 track and autoX events a month. Recently I did a rear diff service with BMW "3bottle" fm booster fluid and during trackday I found the rear diff unlocking on the slower/sharper corners resulting in inside edge tire breaking traction ALOT. Basically need less clutch slip. WHAT DO YALL USE/RECOMMEND, DO YOU USE YOUR CAR ON TRACK??

[Richbot]

Use the Benz/Castrol SAF-XJ 75w140 equivalent without the FM. That's what I'm using in my 114,000 mile car now, and the clutches are loose enough that I don't get any noise. Lockup seems improved but always hard to say if it's placebo effect. Was using the FM fluid before

The generic Castrol is cheaper by a lot, and comes with a fill spout unlike the BMW M FM fluid which is now just shipped in plain bottles with no spout

[E92_Blake]

Thanks Richbot, ill look into it. Noise/Growning is my biggest worry but your very correct that the clutches are pretty loose with this mileage. if I have that issue I can always drain a small amount and add alittle bit of FM fluid.

[Timujin]

This is one handy bottle.

[Ximian]

Liqui Moly diff fluid (LM20042) is a great alternative. No noise and no issues at the track.