hey guys i own a 2010 g37x sedan with 50k and i have never done a flush on any of the differentials. My question is do i just do the flush on the rear or both ?

i hear the rear is the one used for the most part on awd, please if anyone can answer this ASAP

 

I did both, as effort and cost difference was minimal.

Yes, you could tell the rear needed it more.

 

By "flush", do you mean drain and fill?

 

yes drain and refill. im trying buy the gear oil locally is royal purple or mobil one 75 w 90 a good oil to use? i want to do 75w 90 for both i know the manual says 80 w 90 for front but its hard to find locally

 

My local dealer had it in stock for $10 per bottle. It is the factory fill, but it is NOT synthetic.

Many have used a synthetic 75W90 without issue. Use what you can find.

 

Whatever you do, be sure to use a GL-5-rated gear oil. I'd stick with the recommended viscosity, too.

 

so i i got it done used mobil 1 75w 80 and yes its rated gl5. used 75w 90 for both front and rear.