How many of you used the gasket for the 8.8 when taking the diff cover off and who just used black RTV? I've got both and trying to decide if ones better than the other or I should just do both and make sure it doesn't leak.

Second I know with the Amsoil 75W-140 that I have you do not have to add fiction modifier but, can you if you want? I have a bottle of the Ford modifier laying around and might as well use it if it will not hurt.

Thanks

 

The RTV does work quite well. I changed my differential fluid about a month ago and I have not lost a drop through the seal.

If you put a thin bead of sealant on the inner and outer edge of the cover, it should be just fine. You don't need a cork or rubber gasket.

As far as the oil itself goes, I don't know what to tell you about adding the friction modifier. I can't say if it would mix properly with the Amsoil or not.

When you are adding the new fluid I'd sugget that you have enough hose to work with and that the hose is also thin enough to get fully through the fill hole so it doesn't slide out while you pump new fluid in.

Another thing is that you should measure out exactly how much fluid you need before filling the differential because you can actually overfill it and not notice till you drive around a bit and then remove the fill plug to check and it comes pouring out onto the driveway.

 

Well, it's done and I was a little surpised. I figured with my 135,000 miles and the clunking it has been doing I would find metal bits and worn gears. It was much better than what I thought the gear oil was not milky and no chunks or metal at all, actually all I could find was a few microsopic bits. All gears were in great shape and no chips, I am not gear expert but it looked like a good gear pattern to me. I did jack the back up and I turned the wheels by hand to look fully look at all the side gears. While doing this I did notice I could move the wheel and the pinion would move about 1/8-1/4, I guess that is normal slack. It's hard to tell much about the bearing or anything else without tearing it down.
I actually used both the gasket and the black RTV. What I did was spread a thin layer of RTV around the cover flange to hold the gasket on then I laid a then film and a bead. Let it set for a few minutes to get tacky then slapped it on. Tightened down bolts to 32ft lbs in a cross pattern ( top, bottom, right side, left side, etc). I also for the heck of went back and laid a bead right around where the cover meets the diff as that looks like waht the factory did. I picked off huge hunks of the factory RTV off the outside edge. I refilled with Amsoil (no fiction modifier) to fill plug but have not driven it yet. Figured since I am in no rush it could set over night and I can test it tomorrow.