Which Fluids?

[Desertshark43]

So I went to my local NAPA and they have Liqui Moly 10W-60 for the cheapest I've ever seen for a 5L, $43.09!!!
That's not my issue. My issue is the Diff and Manual Trans Fluid. Now for the diff Fluid, my Indy tech says to go with the OE BMW brand, due to the Liqui Moly brand causing friction and noise. I'm fine with that. FCP Euro sells the BMW brand in a kit. Are there any OE alternatives that anyone uses without any issues, for future fillups? Also, the MTF Fluid is a bit confusing. Can I use the Liqui Moly branded GL-5 75W-90 or 75W-80 without consequence? I know the 75w80 is for DCT, and the 75w90 is MTF, but is there really a big difference beside just thickness? Or should I stick with Pentosin FFL-4, which also by the way doesn't give reference as to what the weight is? It does say on FCP Euro that it replaces the MTF-LT-2. Also, does anyone know what the OE actual brands of differential and manual trans fluids are? Lol a bit confusing

[Ximian]

I used the 75W140 LM diff fluid and it works well. Didn't notice any noise since I was enjoying the lack of harshness from the OE diff fluid.

[dparm]

OEM transmission and diff fluids are Castrol.

MTF-LT-2 is actually a 75w80. If you look at Red Line's recommendation of D4 ATF, it's a 70w80. Their tech support guys have said that some people mix the D4 ATF and MTL90 (75w90) to get something close to a 75w80.

Rear diff is 75w140 with LS additive. It's Castrol Syntrans LS (formerly known as SAF-XJ) but with extra FM added to quiet things down. You can use pretty much any 75w140 as long as it has the LS additive -- or just add your own.

[Z K]

^

I've found that diff does not make any noise when cold anymore even without FM additive.

All you need to do is go track the car a few times and it no longer makes noise. I just use straight SAF-XJ. Less slip = more grip.

[Desertshark43]

Originally Posted by dparm

OEM transmission and diff fluids are Castrol.

MTF-LT-2 is actually a 75w80. If you look at Red Line's recommendation of D4 ATF, it's a 70w80. Their tech support guys have said that some people mix the D4 ATF and MTL90 (75w90) to get something close to a 75w80.

Rear diff is 75w140 with LS additive. It's Castrol Syntrans LS (formerly known as SAF-XJ) but with extra FM added to quiet things down. You can use pretty much any 75w140 as long as it has the LS additive -- or just add your own.

What's the LS Additive? Lol what does LS even stand for? Does it come mixed in most of the Diff Fluid brands, or is it something I buy separately and just mix in with the Diff

[Desertshark43]

Originally Posted by Desertshark43

What's the LS Additive? Lol what does LS even stand for? Does it come mixed in most of the Diff Fluid brands, or is it something I buy separately and just mix in with the Diff

Nevermind, I'm an idiot. Limited Slip. Lol

[Desertshark43]

Originally Posted by Desertshark43

Nevermind, I'm an idiot. Limited Slip. Lol

Found it!

[dparm]

Limited slip additive changes how the differential ramps from locked to unlocked. You need it, but the dosage is somewhat to personal preference. I tend to revert to the BMW standard when in doubt, as this is something they would of course test for.

The situation you want to avoid is abrupt transitions from locked to open, or getting into a gray area where it's constantly locking and unlocking. Both of these would unsettle the car and make the handling less predictable.