Hi All, Probably one of the nicest features on this truck is the Limited Slip differencial, my previous 4WD trucks didn't have this feature, which required me to use FWD, now that I have a limited slip rear end, I don't need 4WD, even in snow. I don't do alot of off raod stuff so its all great, my question is, what can I do to preserve the differential and how long can I expect to make it last? I just turned 35K miles and found out Its time to change the Oil, I called the dealer, they recommend 80-90wt and they also add a special additive? does anyone know about this, can you buy it at any auto parts store?