jabara572
Active Member
Does anyone know why the 3.55 and 3.21 axles are recommended 75W-90 gear oil, but the owners manual states 3.92 gears are recommended 75W-140?
I want to do a differential flush and refill at 16K miles just for peace of mind. I cant really see why two identical ZF axles would get such different fluid requirements based on nothing but the ring gear. I dont tow and the vehicle never sees any hard use, just daily commuting and highway. I would switch to a synthetic 75w-90 if it meant less friction/better mpg due to my service but I dont want to damage anything.
Apparently most people who ask the dealer for diff oil get recommended 75W-90 regardless of what gear ratio they have. Im wondering if the 140W is listed just due to the Max tow package durability and nothing else. Thoughts?
I want to do a differential flush and refill at 16K miles just for peace of mind. I cant really see why two identical ZF axles would get such different fluid requirements based on nothing but the ring gear. I dont tow and the vehicle never sees any hard use, just daily commuting and highway. I would switch to a synthetic 75w-90 if it meant less friction/better mpg due to my service but I dont want to damage anything.
Apparently most people who ask the dealer for diff oil get recommended 75W-90 regardless of what gear ratio they have. Im wondering if the 140W is listed just due to the Max tow package durability and nothing else. Thoughts?
