diff oil

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Nov 23, 2007 | 01:28 AM

dadirtydogg

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diff oil

what viscosity of diff oil do i use? was told 75W140... i think that is synthetic, which is the way i was gonna go anyway. have an 04 5.4 with 3.73s

Nov 23, 2007 | 06:25 AM

svt2205

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From: Sunapee NH

That's what my owners manual lists. If it's a limited slip diff, call your local Ford dealer and see if these still need friction modifier.

Nov 23, 2007 | 07:40 AM

1saxman

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Quote:

Originally Posted by svt2205

That's what my owners manual lists. If it's a limited slip diff, call your local Ford dealer and see if these still need friction modifier.

They absolutely do need the limited slip additive.

Nov 26, 2007 | 10:16 AM

Doogie S

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I just did my rear diff and installed 75W90 Royal Purple Max-Gear, as per the factory service manual recommendations.

The rear diff uses synthetic oil. I swapped mine out when I replaced the rear axel seals (one was leaking) and installed the Maghytec cover.

No friction modifier needed...

Doug

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