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Bought some Mobil 1 Synthetic LS 75W-95 gear oil to change the rear diff fluid in the Z06. Mobil website says that fluid already has friction modifier in it:

"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."


Anyone have success running it without adding the GM Friction Modifier in a Z06? Also I know there are tons of you that like other oils (GM, Amsoil, Royal Purple, etc...) but please don't turn this thread in to an oil debate. Just looking for confirmation from someone that actually put Mobil 1 in their diff if they needed additional friction modifier or not. Thanks.

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Vette5.5

My 06' is still running factory fill diff fluid with no additives. The clutch plates do chatter a bit on cold tight parking lot turns, but can easily live with it. I've put the additive in other posi cars, and while cutting down clutch chatter a bit, also took away noticable amounts of straight line acceleration posi clutch pack lock up. I tend to stay away from this stuff now. You can always add this stuff in later, if want to.

triblk6spd

If you are going to use the Mobile 1 LS 75W-95 then I would just add a half ounce or so to the mix just because.

Chonger

I just did my differential. Your probably better off using the latest GM stuff 88862624. It has the additive already added.

If you use anything else I would use the additive.

atljar

I personally wouldnt run any additional friction modifier (ie, lets make your limited slip more limited additive).

If it chatters on hard turns, then add a little in. You will NOT hurt the unit running without it with mobil1

edmundu

I agree, just put in the fluid as is. IF it chatters excessively, then add a little modifier until you're satisfied.

triblk6spd

Screw that..adding fluid after the fact is a Pain in the ***. Just add a little now and be done.w it. Its not gonna hurt anything...

Vette5.5

Gotta disagree with that one "tri". Put some additive in a car's diff, and did not like they way it took away posi lock up action on straight runs. Ended up taking the diff clutch pack assembly apart, and flushing everything. Somehow think holding off a bit on the additive, would be easier than this.

triblk6spd

Lol. Keep in mine I did say only add 1/2oz... Which is what I did and its working excellent. Def good to have the flip side posted so people can make informed decisions.

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Ok thanks for the replies. Was hoping to find someone that had actually tried it. Gonna try the Mobil1 as is then add friction modifier if needed later. At the strip sometimes mine wants to spin only one side so having more friction at the clutches would be better for me. I'll post up my results for captured knowledge.

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Update, put the Mobil1 diff fluid in as is & it's fine so far after 3 days.

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Update, still good. At the drag strip didn't have any one wheel peel issues.

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Still going great with Mobil1 & no friction modifier.

GOLD72

If you haven't been experiencing chatter, the Mobil 1, RP, Redline, AMSOIL products are all already formulated with the slip lock additive and you should be fine without any additional. If you are doing a fluid change due to moderate to severe chatter, I would recommend adding some additional of about 1 to 2 ozs for a Z06 diff. Too much is a bad thing as pointed out earlier as it will disable the positract functionality. The separately purchased slip lock additive bottles are 4 oz in size as I remember.