I have always run Mobli1 in my tranny and dif's. Today was the biannual change the fluids day and I switched the tranny and transfer case to royal purple. HOLLY CRAP what a difference. I had about 35K on the mobile 1 and I was noticing that I had a hard time shifting 1-2 2-1 and 3-2. I figured it was just because I had 140K on the truck, but the thing sifts so much smother now. No problem at all. The truck was really notchy when shifting in and out of 4wd now its real smoth. Only down side is i spilled on the exaust and it smells like ass when it burns.