rearend servivce

[crashz]

Can't hurt to change out the oil. The oil additives do wear out over time and it gives you a chance to pull the cover and check the gears. I've caught a couple broked ring gear teeth on an F350 before we ran into any serious problems.

If its never been done, you'll be shocked at what comes out (or needs to be scraped out)!

 

[schmism]

i suppose that depends on how much you 4wheel it.

if you had the diff underwater it should be changed relatively frequently.

if its a mall crawler/pavement pounder then 50-60K is fine.

 

[mojoinco]

It's cheap and easy to do -- even with synthetic it's still pretty cheap. The large Dana axles use rtv for the gasket. I would find it likely this does too. Get out a bucket and a piece of cardboard, take off the lower cover bolts (sometimes one of these is drilled through the case for draining; otherwise loosen them all up so that you can pry the cover loose). Do it after a drive and on the afternoon of a warm day. Come back an hour or two later and finish (it might be easier to fill if you jack the body up so that the diff is easier to reach). Bet it costs you less than $25 to do.