Transfer case gear oil: Is 75W-90W OK?
 

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!

75w90 may work fine in transfer case
 

After some reading/searching, I found some comments from people asking the same question with their vehicles. Here's a response from Mobile 1 on using 75w90 where 80w90 or 90w is called for:
http://www.mobiloil.com/USA-English/...Viscosity.aspx

Could be propaganda from Mobil 1, but makes sense it's still 90w at operating temperature and it meets the GL-5 EP rating. Comments?

I have used the Mobil 1 product before, as long as it meets the API GL5 its fine....that is the standard that is required etc.