Helloe . I need to change my rear diff fliud in my truck. The owners manual stated that i should uses 75w90 gear oil. It also said not to use any limited slip additive. I know it is not a dana rear it is an aam 11.5 rear which it does not need the additive. What i wanted to know is i was going to use lucas synthetic 70w-90 gear oil . It has the additive allready in it . Will this be a problem and has an one eles ever use lucas oil? I have been told it is as good as amsoil. Any addvice. Thank you

 

Hey Ziggy, the Lucas synthetic will be ok - I have used both Mobil1 and Amsoil in my truck. I usually use 75W-140 in the back, but used to run 75W-90 back there.

You need to buy 4 quarts and you'll have a little left over.