Differential oil for 325is

[DaveInLA]

1989 325is with LSD

I've seen lots of recommendations for 75w90 Redline synthetic, but I've also read that this often makes the differential pretty loud when driving. Anybody have any experience with this?

Also, how do you think 80w90 synthetic (not Redline) compares?

[jase007]

Dave:

I would think both would be OK. Check the manual and follow what it says. I have the redline products in my iX now. Front and rear differentials, transfer case and manual gearbox. Changing fluids on the iX costs some $ . I haven't noticed any increased whining from any of the differentials, transfer case, gearbox since adding the redline. Would have also used valvoline synthetics if I needed to. The main thing is to check fluid levels and not run any of this gear dry. Eventually, the rear diff flange seals leak and need to be replaced as well as the drive shaft / yoke seal. Will probably be doing all of mine when I do the clutch ... at some point.

Jason

[Jared at Pelican Parts]

I run Swepco in mine. No problems for two years now....

[jase007]

jared:

I have actually run Swepco in my P-cars for years. For some reason I went with redline years ago on the BMW. I should change it once and see how it shifts with the Swepco.

Jason

[Jared at Pelican Parts]

I noticed that it seemed to shift a little easier with the Swepco, although that could just be hypoid fumes talking....

[makaio]

Jared, are you running Swepco 80-90W in the diff and the gearbox? I put Swepco in my gearbox this weekend, but haven't got around to driving it yet to see if it made a difference.