So this might sound kinda weird; I'm having a difficult time finding Quaker State ATF+4 and 80w-90 gear oil. Anyone know where to get some of theses? I want to change the fluids in my rear diff and transfer case. I know I can get any ATF+4 or gear oil but I just prefer Quaker State.

Also when I change my rear diff fluid should I add an additive? If so which kind(s) are good and how much should I use?

 

Did you try looking at an auto parts store? If a store (ie napa, advance auto, etc) has quaker state atf/gear oil listed on their website but you cant find it in store, either order online and have it shipped to the store or ask someone at the store to order it for you.

If your rear diff is limited slip (may be indicated on the tag on the axle/diff housing or in glove compartment) then you need to add 4oz of additive such as this http://shop.advanceautoparts.com/buy...rt-402508.html
It's a 7oz bottle i believe so use a little over half, and pour it in before you put in the gear oil.

edit: you can also email chrysler for a build sheet and it will list your differential type. you can also jack up the rear and spin one tire, if LSD then the other tire should spin in the opposite direction (assuming your LSD is in working order.)

 

Apparently nobody sells QS gear oil or atf...
I figured I could find a store that sold it fairly quickly, but no.
Check pepboys, oriellys, walmart, kmart, advance auto, autozone, napa, and pizza hut. None of them had it.

Why quaker state? Oil is oil, any name brand will do. I even use advance auto parts brand gear oil and its been fine so far.

 

Shell oil owns Pennzoil and Quaker State, I don't know if that means they are the same product. A lot of folks are fiercely loyal to a particular brand of oil so if your hellbent on QS I'd simply call Shell Oil and find out what the deal is.