so i here alot of good things on it all the time and i was wonderin if you guys have used there gear oil i was going to when i changed my diff fliud so i figured i would ask the exoerts and see what they say

 

I am no expert but I did use synthetic Royal Purple when I changed my diff oil a while back. I suppose it has been 50k miles now and things are still turning back there. I never took any temp readings nor have a temp sensor installed so I couldn't say if Royal Purple is any better than any other kind.

 

I used nothing but royal purple in the trans in my last vehicle (450hp front wheel drive) and it did great, I never had any issues.

 

I was very dissapointed with it.......the ATF is not purple.

I had a discussion with whitebuffalo, whodoes a lot of the oil analasys for schaeffer oil, and he says not to use it in the rear diff because it's oxidation levels are not acceptable.
If you search for topics on it you will see our discussion (i'll look afte this post. iPhone can't do multiple windows without refreshing the last page, so I'd lose my typing)
I've heard good things about rp ATF in cars. I do not know about in our trans though.

 

First I've heard of the oxidation issue, but I've been running it in my diff for about a year now. You might also consider going with the '08 cover, since you're pulling it anyway. It's only about $50 from Ed. Have a look -- click the pic to take to you to my WebShots album of the swap:

 

Not to be a Royal Purple "nay sayer", but everything that my friend used RP in a gear box turned black & stinky. He burned up two differentials in his company trucks. Also, had it in the final drives of his mini excavator. Oil broke down and did the same thing. Most people have good luck with it, but his experience has been terrible.

 

what kind of fluid do you guys recomend

 

Post 37, last page, White buffalo posted his uoa. Royal purple didnt cut it.
lower viscosity and oxidation.

https://www.ford-trucks.com/forums/9...r-diffs-3.html

 

Oh yeah -- I remember that now. I'll run this OCI out and go to something different. I had a heck of a time finding ANYTHING in syn 75w-140. Too bad Schaeffer only sells it in 5 gal jugs...

 

What did you end up putting in yours, Roland?