time to change my differential fluid, i want a synthetic, most likely amsoil, but my question is my posi is so tight it wipes my rear tires out fast, is there some additive or anything to get the posi to slip a bit more? i figured it would loosen up over time, but i have 80,000 miles now and still drags the rear tires around the corners.

 

I believe there is a additive you can add to the synthetic oil that will allow it to slip. I forget what it is called at the moment but I know others have said put your oil in, drive it around in sharp figure 8's, and if it still isn't slipping then start adding this additive little amounts at a time and then go out and drive it again. If I remember correctly..

 

I used the Amsoil 75-140 synth, and also added the dodge addative, works great for me as I pull my trailer lots.

 

Yup! Test after changing to Amsoil. If still too sticky.... add any brand of friction modified..... small amt at a time, till it is to your liking!

RJ,

 

amsoil 75-140 allready has fric. mod. in it.

 

Get the additive at the dealer.

 

Redline has their own modifier. Some need it, some don't.

 

I changed my diff oil to Royal Purple. I got some crunk-crunk-crunk going around corners when it was cool in the morning. After the truck warmed up some, it would stop. I added 3 ounces of XL3 friction modifier from the Ford dealer and now I can barely detect a little crunk in the mornings. I'm happy and my tires are too! XL3 is the same in Ford and Dodge diffs. (Both are from Dana)