So I guess I'm gonna change oil tonight so I might as well do the rear end and transmission fluid as well.
Was wanting to get some opinions on wich rear end gear oil I should use, and auto trans fluid.
My truck is a 05 1500 5.7 2wd

 

I had really good results in my Grand Cherokee Overland when I changed the oil and both diffs with Royal Purple. A solid 2+ mpg gain over-all. The truck now has RP in the crankcase and when the diffs are due in about 4k miles, I'm gonna use RP there as well.

The only issue I had was about 8k after the change, the lockers in the GC started to chatter a little (RP states you don't need LS additive) I put a bottle of additive in after the chatter started and it quit almost right away. So, I'd put the additive in anyway when you change the diff fluids.
As far as the tranny goes, I'm seriously thinking about Royal Purple in there as well, the Jeep is about due, so it'll get done in the next month or so.

 

Im going to change out my trans fluid soon also and Im thinking about getting a good synthetic oil since i need this truck to last me a while, anyone else have any suggestions?

 

I use synthetic everywhere I can. I just did my rear diff yesterday. I was especially interested in HammerZ71's comment about the Royal Purple. I had noticed they suggested you didn't need the LS additive, but didn't describe how much was in their product. I passed them up and went with Mobil 1 and put my own additive in....that way I know it's got the right amount. But for transmissions, I seem to think you only replace a small amount of the total fluid when you do a change, if that's true I'm not sure adding the synthetic would do help anything.

 

Oh i was under the impression that all of the trans fluid gets flushed and replaced with new. I mean i bought the truck used and figure its never been done before, 38,000 miles now...

 

I just replaced the engine oil, tranny oil, and rear end fluid with Royal Purple. It seems to run smoother, and the tranny definitely shifts smoother, but there was no noticeable mileage increase. It ran me over $200 for all the fluids. After reading about the chatter, I think I'll pick up some of the friction modifier and dump in the rear. Anything to get a gripe form the wife about spending money!

 

I'm one of those that follows a different drummer. I don't normally flush my transmission, although I have done it before. Instead, I take the transmission pan off the first time at the normal change interval, change the filter, then install a drain plug. Thereafter I drain and refill the transmission fluid at every other oil change. That way the fluid gets changed about as often as if I flushed it every 30k or so, and the fluid stays fresher in between. And then I change the filter on schedule. Filter changes are cleaner with a drain plug as well.

This may sound odd, but I haven't had a transmission problem since I've started doing this. I sold my GMC Sierra with 283,000 miles on the original transmission so I could buy the Dodge for my wife. I drive our 2003 Explorer Sport Trac, with 170,000 miles on the original transmission.

The only question I have is how it might affect the lifetime drivetrain warranty on our 2008. I read somewhere that a Dodge service tech. claimed a drain plug in the transmission pan that intruded into the pan would void the warranty. I don't know what to do with the Dodge yet.

As for fluid, isn't ATF+4 part synthetic anyway?

 

Both mobil-1 and Amsoil synthetic ATF fluids are outstanding.

 

so if i go to my mechanic to get the trans oil change done, how many quarts should i buy?

 

I always have my transmissions power flushed. This cleans fluid from the cooler and all.