I hate to be the one to start a thread on anything oil related but here goes. I have a 1949 GMC 1 ton with original 4spd and 302 and did the rear end swap. An old local mechanic stopped by and told me he always mixed 90W gear oil with equal amount STP to quiet the gear whine. He also added "some" STP to the tranny. I'm hoping to do some long distance trips with my truck and would like to reduce noise for driving pleasure. Any consensus on alternate lubricants that aren't snake oil?
I've already used rattletrap on the interior of the cab and topped that with glued on reflectix to help with noise and heat. I'm very happy overall with all the mods but since I will be draining the gear box and diff again soon I thought I'd ask.
