Today i had the front and rear diff fluids changed they used 75w 140 syn.oil in the transmission 5 speed they put in red line MTL. and also had the fluid changed in the transfer case with the same 75w140 syn. Not sure what to look for while I am driving if any difference , would there be any thanks .

 

When i drained and refiled my diffs with 74w140 they were definitely quieter. I dont know what weight of oil was in them when I bought it though.