Looking for a little advice on the gear oil.
I have a 98 T100 4X4 and am planning on putting the royal purple max gear 75W90 in the transfer case. Has anybody out there done this? It says it has friction modifiers in it and just wondering if it will have any ill effects on the transfer case. I also am planning on putting it in the rear diff even though it says it should be 80w90. I don't use it hard and it never gets abused. Very little off road and then its dirt roads with a little mud or snow. Anybody think its a bad idea? I am very new at synthetic oils so any help will be greatly appreciated. My main interest is getting more life out of the components and freeing up some horsepower and maybe even some mileage.
Thanks to all for any advice.

 

I run it in my diffs, tranny and t-case on my 85.

Amsoil that is.
http://www.wabfab.org/products/amsoil/amsoil.htm

 

I run Mobil1 75w90 in the transfer case and diffs.

 

http://www.4crawler.com/4x4/index.sh...ntheticGearOil

 

Ditto, in the syn that is.. i couldnt tell a difference between the m1 syn and the durablend in 75-90.. the durablend held up well on regular highway use for 30k miles