Been seeing a lot of threads but I would like to change my differential and transmission fluid on my 2003 g35 coupe manual. It has 165k miles and im only getting 10-14mpg city driving.

hopeing this with sparks will help solve problem.

My question is what oil and how much for dif and trans?

Also do i need new washer or new plugs? Does anyone have part numbers please?

 

FWD is the table of Contents.

http://psedog.com/cars/fsm/g35/

 

lol at diff and trans fluid replacement affecting MPG. Thanks for the chuckle OP..........

I told you in another thread with your driving situation you're not going to get significantly better mileage no matter what you do.

 

It would help a little. When I changed my diff fluid the first time, the rear wheels were actually hard to turn with car in the air, after putting in fresh fluid, they would spin smooth like butter. Smoother and easier spinning driveline could have a small effect on MPG, but also helps with acceleration from what I've noticed.

That said: OP, fluid types and amounts have been beaten to death.
MT is GL4, 3.25 qts. Use Nissan MTF or Redline MT85. Usually need to visit dealership or order online. DON'T USE A GL5 FLUID IN THE TRANS!!
Diff is GL5 80W-90, 1.5 qts. Most auto parts stores stock this.

 

thanks. do i need new washers or new plugs or just reuse everything?

 

so Mt-85 for MT i guess i need to buy 4 qt

and Mobil 1 104361 75W-90 Synthetic Gear Lube for Diff 2 QT?

 

The manual says to replace the washers, but I never have. YMMV

 

If you've followed Nissan's maintenance schedule and your fluids are in good condition changing it won't effect your gas mileage! If you've never changed plugs or you have the "Check Engine Soon" warning on your dash both these will cause poor mileage. Our first gen G35s don't get great gas mileage around town, open road make sure you use the cruise control...that makes a major difference!
Gary