Rear Diff Fluid Requirements

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Mar 30, 2007 | 04:17 PM

stang3O2

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Rear Diff Fluid Requirements

Notice the Requirements changed to 75w140. Recently installed 4.56s on my 02 FX4 about 500 miles ago and getting ready to change the fluid after the "initial break in" period. Had a buddy who works for VP RACING FUELS and can get me VP-Red 80w140 Synthetic at only $5 a quart. Heck of a Deal!!! Is this OK??? Whats the reasoning for the change to 75w140 from 75w90. Just wondering if there is really much difference and if it will hurt anything going to 80w instead of 75w! Thanks...

Mar 30, 2007 | 04:41 PM

steve(ill)

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that should be fine. the main think is the synthetic does seem to make the rear end run cooler. i stil use the 75W90 in mine, but stick with the synthetic due to the heat and the LS rear end.