if somebody's gonna argue the merits of thinner viscosity in that application, i won't bother responding. the 4.10 lsd is filled from the factory with 75w-140 synthetic oil. i dropped a tube of lsd in there for safety's sake. if you want to use a 75w90 with an LSD additive, feel free to do so, however, that isn't what it came with. i find no gain in fuel consumption using 75w140 over 90.Originally Posted by atomicDog