Ford 9" recommended gear oil?

[Reddzedd]

So, I recently bit the bullet and ordered a 9" rear end kit from QuickPerformance for my '78 Malibu. Along with it I received a card saying it requires 80W-90 GL5 non-synthetic gear oil with Posi additive. I was wondering if anyone that has used a swap kit, or just have owned a 9" in the past, which gear oil you would recommend? Is there gear oil out there with additive already in it? Or do I have to buy the oil and additive separately? Any brands I should consider over others?

 

[melloelky]

i swapped out mine last year with one from them with the trac loc,I'm running the Lucas.they claim you don't need any additives.I've had good luck with it,no noises or any issues last year.

 

[fleming442]

It really depends on which differential you got. My True Trac didn't like the 80w-90, and chattered a lot on tight turns.

 

[TURNA]

Differential/center section dictates the oil and additives not the rear end housing!!

 

[pontiac guy]

Differential/center section dictates the oil and additives not the rear end housing!!

X2

Cone type has different needs than clutch type. Go with what the differential manufacturer recommends

 

[pontiacgp]

are they not using the carbon fiber clutch packs yet?

 

[57 Handyman]

Do what the manufacturer recommends...and do NOT use synthetic! I had two different posi rears; previous owners had synthetics and adding additives did not make a difference with binding of clutches.

 

[Northernregal]

I used royal purple synthetic and some trac-loc friction modifier from ford that I got from Quick Performance. Seems to be working for me. Rebuilt 31 spline trac-loc in a QP housing.

 

[pontiacgp]

not that long ago Eaton only recommended conventional oil but Gm trucks with the Eaton posi used synthetic from the factory. Eaton has not changed any material used in their posi carriers but Eaton has finally woken up

Eaton Posi™
Quality mineral or synthetic lube with sufficient friction
modifier content will ensure the smoothest operating
and longest life of your Eaton Posi performance
differential. Eaton recommends GM Dexron LS or
Castrol Carbon Mod SAF (Synthetic Axle Fluid) for all
Posi applications. If using non-“LS” gear lube, add four
ounces of General Motors “Limited Slip Axle Lubricant
Additive” per one-and-a-half quarts of gear lube (GM
P/N 88900330/10-4003). Additional friction modifier
additive may be used to reduce LSD plate “chatter,” but
do not exceed eight ounces per one-and-a-half quarts
of lube. Other brands of additives may be used. A
friction modifier's purpose is to lower the static
coefficient of friction (grabbing) within the clutch to
match the dynamic friction (sliding) in an effort to
reduce the effects of friction transition (stick, slip,
chatter). Excessive amounts of a friction modifier can
lower both friction values, resulting in reduction of bias
ratio (performance) for plate-style limited-slip
differentials such as the Eaton Posi. Many brand name
gear lubes contain some limited-slip friction modifier in
their formulation. If you use such a lube, additional
friction modifier additives should be used sparingly to
avoid accidental over-saturation resulting in
performance loss.