I'm doing a F&R gear swap(4.10 to 4.56)in my 02 2500 Suburban and I was wondering what you guys would recommend for a break in Gear oil in a 75W-90. Since this oil is only going to be in the Diffs for a short time I don't really want to go to the expense of buying Syn for the break in unless it is neccesary. I plan on using syn after the break in period. Also, if 75w-90 is the recommended oil viscosity would it hurt to go to a 75W-110 or a 75W-140 after the initial break in period for a little more protection? I had so many different answers from people I thought I would check with the experts on this site.Thanks in adavance
