Sterling 10.5 F-350 Rear Differential Gear Lube ?
I just recently bought a F-350 7.3 2002 with 180,000 miles. I went through and changed all the fluids last week to synthetic. In the rear differential I put Amsoil 75W-90 thinking it was the DANA 80 which it calls for. However, I discovered after the job that it is the Sterling 10.5 and requires 75W-140. Will it hurt the differential to keep the 75W-90 in there and continue to use. I tow a boat frequently also. Also, I am receiving a slight hesitation upon acceleration from a stop, but at no other time. Could this be that I need to add some friction modifier to the rear differential?