I began to notice a few months ago that when I accelerated out of a sharp turn from a stop (like in a parking lot or leaving a parking lot) there was a rhythmic vibration that felt exact like I was driving over rumble strips. Then it would go away. Like it would be: brump, brump brump brump that got faster as I sped up. Maybe 2 to 4 brumps, then nothing. I thought that I would change out my diff fluid and add the friction modifier. Well, the only gear oil that they had in 75W140 was Royal Purple. WOW! They ought to call it liquid gold! Anyhoo, I got to siphoning that stuff out and it smells so bad. I spilled some on the driveway. Man! That stuff is nasty and sticky and thick like honey....and it smells horrible.

But, got it changed out before our camping trip to CO.

My tips for the newbie:
1) Don't buy the bulb style siphon pump because it doesn't work. Get the vacuum gun/squeeze handle with gauge and collection jar. You have to empty the bottle several times, but you get it done pretty quickly.
2) Probably should have had the diff hot from driving. (maybe the bulb would have worked with hot oil)
3) Kitty litter.
4) Brake cleaner to clean diff off with.
5) Did I mention kitty litter?

But, the vibration appears to be gone!

cheers!

 

Is that a LS rear end?

 

I thought all Excursions were LSD.

 

Nope. 'twas an option.

Gear oil = olfactory nirvana!

 

hmmmm. oh well, the owner's manual said to use that weight gear oil and add the friction modifier. I just assumed all of them were LSD. If it isn't, guess it won't hurt.

 

It is a LS and needed modifier.

 

Did you pull the cover or just siphon it out?

I changed mine 20,000 ago and it needs it again, I even used Mobil Synthetic that was supposed to have FM in it.

 

You can just add FM.

 

I siphoned it out.

 

Are the owners manuals specific to the truck then?

 

You might want to pull the cover next time, that wasy you can make sure you got all of the old oil out.

 

It probably would have been easier as well....

 

No, the LS designation is on the door sticker and on the diff tag.....usually.

 

I would pull the cover off next time. the gasket is cheap to buy...even cheaper to make.

that way you can get in there with carb/brake cleaner and get all the old nasty crap out

 

Plus you don't even need a paper gasket.