killagt

iTrader: (3)

Today im changing my rear end with mobil 1 75w90, I call the chevy dealer and find out it close down, and closer to me is 30 min away, i call em up and they dont have any more, but it cost $12.95 a bottle, I just wonder its ok to add that ford stuff to chevy rear end ? I still have 4 bottle of that ford thing ( I preview owner of mustang lol ). does any one here use it ? thanks, Im not changing rear diff until I find out its ok to add .

00pooterSS

iTrader: (40)

It should be fine, its just friction modifier and so is the GM stuff. Also they sell friction modifier at the auto store too.

ALSO you only need modifier if you have an auburn posi. If its the factory posi it will most likely be a Zexel, Zexels are gear type diffs and do not need friction modifier.

And for what its worth the rear end shop had to use non sythetic rear diff fluid and 8 oz of friction modifier to keep my auburn from squalling during cornering

Jawsgear

iTrader: (2)

Ford additive will be fine.

MeentSS02

iTrader: (11)

I'm currently running Ford additive in my Strange 12-bolt - the posi seems to chatter less with this stuff than it did with the GM additive, but that could just be my imagination. I'm not sure what the specs are between the two, but at this point, I'm not expecting catastrophic failure.

00pooterSS

iTrader: (40)

Mine chattered with 75-140 (synthetic) and 6oz of Auburn additive. With GM 80-90or it may be 75-90(non synthetic) and 8oz of GM additive its fine and the posi still stays locked in pretty tight even under normal driving. If that helps at all.

00pooterSS

iTrader: (40)

TO THE OP

These are pics of the different diff's, If you have the Zexel, the one with out springs you dont need the additive, if it has springs then its an Auburn and you do need the additive.

99'CajunFirehawk157

iTrader: (57)

Get this, in mine a gm dealership did a fluid change and put a gasket on with the auburn cover blocking the holes and they never added the posi additive!! Soafter some rtv on the cover and dyno fluid w/ 2 bottles of gm additive later, its super quiet.

BTW- NEVER add syn fluid to Auburn posi's, ONLY Dyno as SYN eats/pits the bronze they say?

killagt

iTrader: (3)

I guest some time cheap stuff work better then high price stuff, like I change my m6 today with cheap oreilly dextron and it made big different on shift and down shift.

Imma drain the rear diff this weekent, and look inside see if I have that spring, If I dont, I just go with valvoline dino 80w90 with ford addictive ( that wat I say I need to use on the manual ). if I see the spring I buy mobil 1 75w90 with ford addic, thanks every one.

Jays_SSZ28

iTrader: (2)

Auburns can't use synthetic gear oil.
They also don't like the friction modifier in the tube that autozone, etc sells.

Auburns tech line told me they get several calls a day due to chatter caused by cheap FM.

They told me to use GM gear oil and ford or GM friction modifier.
So I got some GM gear oil but they were out of FM.
I went to ford to get the friction modifier.
It worked fine after that. GM oil and ford FM mixed together.

killagt

iTrader: (3)

one last question, I go check my ford friction modifier bottle today, and i think it support to smell really bad, cause I KNOW THAT SMELL !, but this bottle doest not have that bad smell at all. I think it been over year since it on the shell. its ok to use it or just buy new one.

AR15 guy

iTrader: (1)

Ok, if I have the differential to the left above I just need to use synthetic 75w-90 and no additive? Once I get my axles I will be re-doing my axle bearings and seals. If I do not need that posi additive I will just skip it.

00pooterSS

iTrader: (40)

No... If you dont have the spring then you have the Zexel and you are okay to go ahead and use synthetic, if I remember right mine called for synthetic, and it has the zexel from the factory

If you have the auburn go with 80-90 non sythetic and use the GM or Ford additive since someone mentioned that the auburn does not like the autozone stuff, I had to finally use GM 80-90 and 8oz GM modifier to get my auburn quiet.

Mine chattered repeatedly when an aftermarket diff fluid and auburn friction modifier were being used, but I think that fluid was synthetic and you are not supposed to use synthetic as stated by auburn

I dont think the modifier smells, but the differential fluid smells horrible

Correct... no springs, no additive.

Zexel diff uses worm gears to apply pressure to the side gears to lock the diff, its all metal on metal. A clutch type diff like an eaton or auburn need modifier to keep the clutches from locking down under normal light driving during turning.

MeentSS02

iTrader: (11)

The last two bottles of friction modifier I've used (Torco Type F) didn't smell bad. I'd just pour it in and go.