Im changing the fluid in the rear end this weekend. its a 9.25 with anti-spin. The service manual says to use 75-140 weight in the rear, but Ive also heard you're supposed to use 75-90 weight... so which is the correct one to use? Also, if you use royal purple you dont have to use the friction modifier right?

 

75-140 in the rear and if you have 4wd, the front takes 75-90.

 

75-140 in the rear, mopar calls for full synthetic. RP has friction modifier in it but some find the LSD ratchets and some don't. Rule of thumb, don't use modifier, run you some tight circles and figure 8s and if it ratchets or makes any noise add half the friction modifier you would normally use...

 

ah. well I might just get valvoline or mobil full synthetic and add the mopar friction modifier just to be sure. As long as it doesnt make noise It'll be fine. It only has to last till spring anyway when I do a truetrac and 4:10 gear swap

 

so I ended up getting mobil 1 full synthetic 75-140 then went to the stealership and bought a 4 oz bottle of friction modifier. I should just pour the whole bottle in correct?

If I get the cover off and find part of a c-clip Im gonna be pissed. In fact... if that happens I might just have it towed to my neighbor's transmission shop and order a truetrac and 4:10 gears right then and there. My neighbor owns a very reputable transmission shop in town and he told me if I bought all the stuff he could set up the rear end for like 300$.

Last time I did something like this I pulled the transmission pan off my dakota and found half of the overdrive snap ring stuck to the magnet. somehow it still lasted 80k miles with no problems though.

 

Hammer what are you talking about modifer and figure 8 aand tight circles thanks

 

If the LSD doesn't have enough modifier it will bind slightly on real tight turns where one side wheel is moving at a different speed than the other side. A few real tight turns will let you know if the modifier in these fluids that say they never it is enough or not. If running a fluid without modifier in it, then just dump in a standard 4 oz. bottle...

 

Rather then start a new thread since this is relevant to the discussion....

I know the fluid capacity for the 06' 1500 rear differential in quarts. But using the hole in the cover as a guide, where should it be when you check it? I have heard

"Right level with the bottom of the hole".

Then people have said "It should be oozing out slightly when you pull the plug"

Then i have heard 3/4" below the hole.

Which is it? And realistically, i can understand the damage potential if it's too low since it will not travel down the axle tubes. But if the fluid is level with the hole vs 3/4" below it, is their any real threat?