Diff fluids

[Covrace]

I want to change the fluid in both front and rear diff as well as the transfer case. Now for the diffs, what fluid can I use: 80w90? 50weight? atf? For the transfer case, The case says right on it to use atf. Can I use something else like 10w30??? ATF is really a bad lubricant, just ask any serious mopar turbo fan..... I had an 86 laser with a 5 speed stick and after I drained the ATF and refilled with 10w30....MAN WHAT A DIFFERENCE!!!!!
So talk to me!!!
thanks!

 

[AgExplorer]

Jake,

You may want to consider AMSOIL's Series 2000 75W-90 Gear oils. In most automotive applications, it will go for the life of the vehicle. Class 8 trucks (the big tractor-trailer rigs) using this product have realized a 4.83% increase in fuel mileage, just by using this. And for the transfer case, try our ATF. Lasts 3 times longer than conventional ATF. Both products will reduce operating temps 20 to 50 degrees F. With all the electronic gizmos they are using nowadays, I would stay with the factory recommendation.