Question about Gear Oil in a Limited Slip Diff

Chris @ GATR · 09-28-2007, 07:18 PM

Does anyone have an opinion or know if it is true that you can eliminate "friction modifier" if you run synthetic gear oil in a limited slip differential? Generally with dino gear oil, you want to run a friction modifier, but I have stumbled upon the suggestion that you do not need friction modifier with synthetic gear oil.

**kingvm** · 09-28-2007, 08:43 PM

I think most gear oils already have it now.

I never added any on my trackloc when I had the d35 and it worked fine. The 8.8 has about 2k miles since I put it in and didn't add any for it either and it works fine.

SWAMPRNR · 09-28-2007, 08:56 PM

I know the MOBIL1 75w90 and 75w140 i get at my shop doesn't have it and requires it to be added to the diffs as needed . I was told by MOBIL they did not offer it in any of there syn. gear oils. Most DINO 80w90 does have it.

gdl · 09-28-2007, 09:10 PM

I just went to the Mobil website and this is what it says for the 75W-90 synthetic:

"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid. "

edzakory · 09-28-2007, 09:13 PM

I use Royal Purple Max-Gear and it does have the limited slip additive in the oil; the label specifically states it. I would check the bottle label on others to be sure.

Chris @ GATR · 09-28-2007, 09:13 PM

Excellent. Thanks.

**2jhanna** · 09-28-2007, 10:48 PM

some gear lubes say "safe for top off" in limited slip applications. if you are changeing your fluid and the bottle says this, you need the additive.

alvinl · 09-28-2007, 11:02 PM

I used the Mobil 1 75-140 in my 8.8 and it has worked great with no modifier.

SWAMPRNR · 09-28-2007, 11:30 PM

Quote:

Originally Posted by gdl

I just went to the Mobil website and this is what it says for the 75W-90 synthetic:

"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid. "

Will have to check this out, bought 10 gallons last week and was told by MOBIL the LS was not out yet.