Differential maintenance

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Jan 30, 2009 | 03:07 PM

desert sled

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From: Northern Nevada

Differential maintenance

I am about to service the differential on my F-350. The ID tag says that it has a C5 differential,therefore it is a limited slip. The manual says to use 75/140 synthetic oil. Do I need to use a friction modifier if I use this synthetic? also i heard of a guy burning up his rear end after using the synthetic. Please help.

Jan 30, 2009 | 05:40 PM

Dave Sponaugle

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Joined: Nov 2003

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From: Nutter Fort, WV

I run synthetic, no problems.
I also have limited slip and I do run the friction modifier.

Jan 30, 2009 | 07:31 PM

desert sled

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From: Northern Nevada

Thanks for the response Dave,I will use both.

Feb 1, 2009 | 05:13 PM

ford trans tech

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genuine motorcraft syn. gear lube does not require the limited slip additive
i would add it to all others
the rear end wouldnt burn up without it it would just have a chatter on turns