Changing differential fluid

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Jun 12, 2018 | 04:19 PM

F0rdF0rever

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Changing differential fluid

Just picked up the mobile 75w140 for my diff. It's says it contains friction modifier. Should I add other ford additive to it anyway?

Jun 12, 2018 | 04:32 PM

bismic

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I don"t .

Jun 12, 2018 | 06:57 PM

DSMMH

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Agree with Mark. If the diff fluid is synthetic, then I would not add the Ford friction modifier. Now having said that, I have 6 quarts of Royal Purple 75W-140 synthetic (I have a large diff cover) diff fluid in my diff and 10oz. of Archoil 9100 friction modifier. With so much rain, not hard to check my diff for proper operation. Works great.

Ed

Jun 12, 2018 | 08:15 PM

F0rdF0rever

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Filled it up without the additive. Thanks guys.

Jun 12, 2018 | 09:05 PM

FiznUKa

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From: Salt Lake City, utah

Is your diff a limited slip?

Jun 13, 2018 | 06:03 AM

Yahiko

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From: Spanaway

When I changed mine on the old truck it was with Mobil1
and going around corners it would make noise. So it got
a little bit added at a time until is stopped making noise.

Jun 13, 2018 | 06:15 AM

bismic

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I would certainly do the same (adding the extra friction modifier), but mine has never made noise. Right or wrong, I have been using that fluid without extra friction modifier for 150k miles.