At some point, when the east coast weather gets a bit warmer, I'll do my tranny and transfer case. The repair manual suggests API G4/G5 in the SAE 80W-90W range. Seeing that it rarely gets below 0 degrees in the Philly suburbs, 90W hypoid gear oil is the requirement. However, I have a bottle of Valvoline synthetic 75W-90W gear oil in my garage (http://www.valvoline.com/products/br...er/gear-oil/59
). Would this be OK to use? Does the weight range matter in this case? Would this oil be too thin? Thanks!