I have been reading some posts on another site about the need to replace rear diff fluid because it has turned black and has big metal shavings in it. Many of these people that posted this also said that it smelled real bad. What would cause this? I know there has been some talk about problems with rear diffs in FJC's that were built prior to Feb 07, is this correct? Also what type of driving would cause this to happen? I have not checked mine but will have the dealer look at it when I take it in for the oil change this time around (it is free, the oil change) Should I have them do a 4x4 service? When should this be done? I have done some mudding in a few cornfields but have not ran with the rear diff lock on. I have used it a few times but not when running fast. At what speeds should you run and not run your rear diff and in what conditions?
Thanks, fatback
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Re:Rear Diff fluid replacement
Date: 2008/01/04 02:33
By: Runner_Ryan
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Posts: 1426
Once the rear diff lock is engaged, speed is quite irrelevant. Besides different handling characteristics, there is no real change to how the diff operates. It wouldn't hurt to change the diff lube. Now that it's broken in, it might be a good idea to switch to synthetic. Oh, and diff lube ALWAYS smells bad.
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Re:Rear Diff fluid replacement
Date: 2008/01/11 14:44
By: kokopelli
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Posts: 54
I've also read that folks are a little concerned and are changing lube quite a lot. It was the same on the Jeep forums for the Rubicon (former vehicle). It's difficult to determine the best course of action. On the Jeep a diff change was scheduled at 24k, but people were doing it all the time. Unless I missed it, it's never mentioned in the FJ scheduled maintenance guide! I agree with Runner_Ryan that it would be a good idea to change it after a reasonable break-in and use synthetic. Beyond that and if no other indicators are present, I'll change them every year (~15K). Who really knows? Ron
Runner_Ryan wrote: Once the rear diff lock is engaged, speed is quite irrelevant. Besides different handling characteristics, there is no real change to how the diff operates. It wouldn't hurt to change the diff lube. Now that it's broken in, it might be a good idea to switch to synthetic. Oh, and diff lube ALWAYS smells bad.
Post edited by: kokopelli, at: 2008/01/11 14:44
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