Which gear oil & gasket for fox 8.8?

HaynStang · Jul 7, 2008

Couple easy questions I'm having a tough time finding the answer to...

I'm changing out the axleshafts on my '90 GT. What weight gear oil does my rear axle take? Is there a real benefit to running synthetic? If I use a synthetic, do I still need to use friction modifier (I have heard that you shouldn't)?

Someone mentioned a good rubber gasket for the 8.8 that was available from Ford. Does anyone know what application this gasket is for (year/model), and how much it costs?

Mustang5L5 · Jul 7, 2008

Just use RTV on the cover.

Run a bead on the cover, let it set up 10 mins and then bolt it on.

In fact, when i changed the fluid on my '03 and took the cover off, there was no gasket. It was just RTVed

Black_02_GT · Jul 7, 2008

just use the RTV and you shouldnt have any leaking problems as long as you get it over the whole thing... no use in spending money for the gasket

rd · Jul 7, 2008

I typically use something like conventional Valvoline 80-90 gear oil and one small bottle of Ford Friction Modifier. Its worked for 20 years.

I did notice that my 02 Explorer and my 08 Bullitt call for synthetic.

I have never used a gasket on a 7.5 or 8.8 axle, always blue RTV.

theconductor · Jul 8, 2008

I just replaced my axles, and like everyone ahead of me said... no gasket, just rtv. Works great. I also used Royal Purple 75-90 and friction modifier. No problems so far....

-kyle

HISSIN50 · Jul 8, 2008

I'm the oddball I guess. I use the gaskets (the embossed rubber over metal gasket is nice).

I like synthetics since the fluid stays put for some time. They offer much greater cold flow capabilities, as well as hot protection. Later 8.8's used a heavier weight of synthetic, wihch indicates to me that there was a reason for it.

Remember the FM reduces the coefficient of friction. If your rear end chatters with fresh fluid, you can add it easily. But you can't remove it. The heavier weights of synthetic often don't include FM in the proprietary blend, so adding it can be wise. The lighter weights often do include a FM in the proprietary blend.

Good luck.

gstang93 · Jul 8, 2008

Working at a Ford dealership i'll list what the mechanics use :
for the gasket use rtv part number ta-30
for fluid everything is replaced with 75w140 synthetic part number xy-75w140-ql
and yes the guys do put friction modifier in part number xl-3
Other dealerships might do things a little differently but that's what works for us.

Shakerhood · Jul 9, 2008

HISSIN50 said:
I'm the oddball I guess. I use the gaskets (the embossed rubber over metal gasket is nice).

I like synthetics since the fluid stays put for some time. They offer much greater cold flow capabilities, as well as hot protection. Later 8.8's used a heavier weight of synthetic, wihch indicates to me that there was a reason for it.

Remember the FM reduces the coefficient of friction. If your rear end chatters with fresh fluid, you can add it easily. But you can't remove it. The heavier weights of synthetic often don't include FM in the proprietary blend, so adding it can be wise. The lighter weights often do include a FM in the proprietary blend.

Good luck.

Guess I am an oddball too as I run the Ford Racing Rubber Gasket on my Stang!

Which gear oil & gasket for fox 8.8?

HaynStang

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Mustang5L5

That is…until I whipped out my Bissell

Black_02_GT

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rd

theconductor

HISSIN50

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gstang93

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Shakerhood

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Which gear oil & gasket for fox 8.8?

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