Mobil 1 synthetic in 8-3/4 suregrip rear

[Husker Cuda]

Anyone know if you can or should use Mobil 1 synthetic rear end lube on a suregrip rear?

[Chryco Psycho]

sure I just filled mine up , just make sure you add friction modifier if the clutches grab

[Husker Cuda]

great, thanks Chryco!

[Chryco Psycho]

 

[MJB]

Good timing on this thread.  I have an Auburn limited slip posi in my 8 3/4.  I just contacted Auburn to ask them the same question.  They advised against using synthetic gear lube.  They claim that synthetic lube can cause severe chatter and can polish the gearing which reduces the effectiveness....their words, not mine.   They told me to use regualr 80/90 gear lube with a friction additive. Either theirs or one of the OEM additives at a rate of 3 oz. per quart of lube.    They claim that they have done extensive testing on this issue.   I was planning on using the same synthetic I use in my Jerico transmission but now I may not after talking to them.  Hope that helps.

[GoodysGotaCuda]

Wow thats interesting to hear. We had a BMW M5 in the shop not long ago that called for synthetic gear lube in the diff.

[Husker Cuda]

Well mine now has Mobil 1 synthetic in it so I will have to report back if I have problems but no more miles than I will drive I doubt if I have any problems.   

[Chryco Psycho]

Mine to but then I don`t have an auburn suregrip either

[Cudaah]

I just had DTS install a 4.10 in my car and they said the same thing.  To use regular lube instead of synthetic but to add the modifier. 

[74 340 4speed]

Good timing on this thread.  I have an Auburn limited slip posi in my 8 3/4.  I just contacted Auburn to ask them the same question.  They advised against using synthetic gear lube.  They claim that synthetic lube can cause severe chatter and can polish the gearing which reduces the effectiveness....their words, not mine.   They told me to use regualr 80/90 gear lube with a friction additive. Either theirs or one of the OEM additives at a rate of 3 oz. per quart of lube.    They claim that they have done extensive testing on this issue.   I was planning on using the same synthetic I use in my Jerico transmission but now I may not after talking to them.  Hope that helps.

Eaton told me that as well.  I have one of their posi units in my 67 camaro and they said that the synthetic stuff causes excessive chatter.  I used lucas 80w90 in mine and haven't had a problem with it.  It has the posi additive already mixed in too. I use the same oil in my Muncie 4 speed too. 

[RaptorF229]

I use amsoil 80w90 with slip additive. No problems

[71chmark]

Why would you need a slip additive? Isn't that what oil is for? Do I need it in my A833?  I just filled it with 80/90 until it came out the fill hole.

[Chryco Psycho]

with synthectic in the rans you need a friction modifier to reduce the slip so the syncros will grab , using 80/90 in the trans you do not need a friction modifier , in the diff it is the other way round you need more slip so the clutches do not grab

[Changin Gears]

On current Chrysler trucks and Jeeps, synthetic 80W-140 gear oil (with friction modifier if needed) in the axle, is part of the towing package.

About 15 years ago Chrysler was using engine oil in stick shift transmissions.  This seemed like a much better idea than the muscle car fill of either ATF or 90W.  I've been using engine oil ever since in my street cars.  They shift great like this hot or cold.