I am getting everything ready to change all the fluids in my truck, rear diff and tranny mainly, tranny is still under warrenty so it gets the syncromesh till the warrenty is gone, my main question is what is best for the rear diff, regular dino gear oil or go with the synthetic, royal purple, mtl or amsoil.
what do you guys use/recommend.

thanks
Eddie

 

Amsoil Severe Gear all the way, proven 20 degrees cooler in a heavy loaded diff, and thats vs. redline.

 

I would have to agree And I should have had to data to prove it by now but it's still not out. We have a comparative data white paper coming out any day I hope. It was suppose to be here late July???
It will definitely open some eyes and make those who have chosen AMSOIL #1, and maybe Mobil 1 #2, a little at ease.
You can't go wrong with either. The new 75W-110 is ideal. It's in the same viscosity range as the 75W-90 was til they changed it a year or two ago.
Heath

 

I have a mag-hytec rear diff cover with a temp. gauge, When I am pulling
30k worth of hay and trailer behind me for 100 miles my rear end temp used to get up to 240 degrees F with redline oil in it, did a couple of trips with castrol synthetic gear oil same thing on the temps. I put Amsoil severe gear in it now the hottest I have ever seen it is 210 degrees F. I couldn't be happier with this stuff. Running around empty I have never seen it higher than 150 degrees. With these temps. I can go a long time with out having to change oil. I have changed rear diff oil in this truck that came out black as tar with only 2.5 months and 19.7K miles on the oil this was pulling just travel trailers from IN to CA last summer and before the mag-hytec cover.

 

thanks guys, looks like i need to find an amsoil dealer close to me, was thinking about going with royal purple, but after do some research and reading the amsoil website i am going with amsoil.

Thanks again for the replies
Eddie

 

I've used both AMSOIL and RP and am completely happy with both myself, I am running ASOIL right now. But deffinately go Synthetic, even your owners manual will tell you that before doing any towing to switch it over. The only thing i run dyno oil in is the motor oil itself. It's just to expensive for me to use it, and I know it is supposed to extend change intervals but I still end up changing at about 4000mi anyway. It's just habit.