Got to Mobil, they say they are the best. Go to Rotella, they say they are the best. Go to Amsoil, they say they are the best. Go to .... Well, you get the picture. What is THE BEST oil for our trucks? Not just the engine, I'm talking the engine, trans, rears and anything else that has a little puddle of lubricant in it. I have been running Amsoil 15-40 since the new engine, but cringe when it's time to change. - What are the benefits of synthetic vs. dino? - What is the best dino? - What is the best synthetic?

Must be the same deal as 12v's. 1994 ones used 10 quarts and 95'+ used 11. First time I changed it I was a quart low, listened to a 1994 guy

And the 3rd gens take a full case or 12 quarts!!!!

I have amsoil everywhere, even got the PS fluid changed out last month. I run the AME 15w-40 and have been getting good results. Should get 20K+ out of this change.

Running Amsoil throughout as well, except for the tranny. It calls for 50 weight ATF that would be used in an Allison automatic. But the last time I picked up some synthetic lube at FleetPride, their own brand that is more like a gear lube, the guy at the counter said' "every one is using this in their trucks". It shifts just fine in all temps, quieted the gear box down, and it offers more lubricity then the ATF. The only drawback to that Fuller Eaton is you have to buy the fluid in 5 gallon pals, so I can get 2 changes out of it any ways. In the engine, I use the 15w 40.