I just did a rear diff fluid change yesterday, but forgot about the transfer case. I went to the local Honda dealer intending to buy the oem 75w-85 gear oil that Honda/Acura uses.

The guy at the parts counter talked me out of it - he said I'd be paying $30 for a single quart when I could just go to Napa. I said thanks for the info.

Now, the thing is, most of the gear oil I see is 75w-90. Is that 5 degree difference really going to affect anything? I am uneasy about putting non-oem fluid into the car, but I have heard good things about redline synthetic.

Just seeking any advice for those who have done this themselves. Thanks!

 

FYI: Amazon has the Honda gear oil fluid via Prime for $24.99. I figured the extra few dollars vs. aftermarket was not worth the savings.

 

That's right, this is a primitive transfer case with two gears inside, you can fill any 75W-85 or 75W-90 gear oil. https://www.mrtonneau.com/75w85-vs-75w90/

 

Thanks for the feedback guys. I think I'm going to roll with the Valvoline full synthetic 75w-90. Reviews are outstanding, without breaking the bank or sacrificing quality. I'm currently doing every single fluid in the RDX and (besides the engine oil) this might be the only non-oem fluid I use. I'll try to remember to provide an update here the next time it hits the change interval.