I had my truck changed after 140k miles. Sure it was dirty and nasty in there, but there were no issues with the rear end. You don't have to change it out every 30k miles. Most people never change the fluid in the dif, it doesn't need it that often at all.

Trans fluid is another thing you need to be careful with. Over age, transmission bands, clutches, and all break down and deteriorate. And if you put fresh fluid in an auto that has 100k on it's older fluid, it may start to slip as the fresh fluid and detergents open up clutches and such. It's something you have to be careful with.

 

I jus changed it. Damn both fluids still clear jus a little dark. Idk when the previous owner changed it. But nice to have 1-2 gear not grind or get stuck anymore n peace of mind for another 60k. Gonna keep this car forever

 

My car has LSD and at about 70k miles, the rear wheels were actually hard to turn with the car jacked up. Changed the diff fluid, and the wheels were able to spin like butter. I can imagine the reduced resistance allowed for better acceleration and MPG.

The FSM states 80W-90 GL-5 for the diff. The 75W-140 is thick and is used for Titan trucks, too thick for our cars. If you want synthetic for the diff, then Mobil 75W-90 is okay, or go with the synthetic blend at 80W-90.

For the manual trans, you need 75W-85 GL-4. The additives in GL4 are different than GL5 and using GL5 fluids will cause damage to Nissan transmissions. Use the dealer stuff, or Redline MT-85 ONLY.

As far as how often, the FSM periodic maintenance does only list "Inspection" of fluids every 15,000 miles. But Brake pads are only "Inspected" as well and we all know those have to be replaced at some point, it's the same with diff and trans fluids. Every 30K miles is a good preventative maintenance interval for those 2 fluids. You'll probably also notice smoother shifting plus less 'notchiness' in the winter after replacing trans fluid.

 

wow ok dude(s). clean oil vs. dirty black oil is the same thing. whatever you say. go drive your car.

 

Your right Gary! These are words of wisdom.

 

Yep, Color is definitely not an indicator of condition.

 

Lol this guy. U do realize that u can drain Ur oil n fill it n drain again some miles after and the oil will be dark becus its mixing with the old oil.

 

The manual says to change it every 30k if ur towing a trailer, camper or driving in muddy or dirt roads. Basically driving the car like a full size truck.

 

I think you are missing the point. People are simply trying to recommend diff fluid changes based on the conditions that exist (weather, heat, etc.) Color can sometimes be an indicator of condition of the fluid and sometimes not. There are racers out there that change the diff fluid and oil after every race due to extreme heat and oil shearing. Dont get me wrong, if you just cruise to work and through the mall parking lot you dont need frequent changes, but we all drive different and therefore protect our machines at different levels.

 

I think u missed the point

 

Your absolutely right I'm wasting my time here. This topic has already been covered 10x's over. Im now going to do a complete analysis of my fluid based totally on flavor and color alone.

 

I have a 350Z HR 6 speed with 52K miles and I'm going to change BOTH trans and diff fluids at 54K. I think 50-60K is a good time to do this...and it doesn't take a lot of time and $$. After a LOT of research, I decided to go with FACTORY trans oil (75W85). Since this isn't easy to come by (discontinued?)...Redline MT85 would have been another choice. Make sure it's GL-4..NOT GL-5. For the diff, I went with Mobil1 75W90. This must be GL-5 and MT-1 rated. You can also go with the 80W90, but that's limited...just make sure it's GL-5.

 

^ur supposed to use 80w-90 for the diff. i went with valvoline durablend. theres also castrol. oem uses pennzoil.

 

True...but a good synthetic 75W90 (M1 or Redline) will be superior to many of the 80W90.

Here is an extensive test comparison done some time ago on gear oils.

http://www.oilteksolutions.com/GearLubeWhitePaper.pdf

Scroll to summary chart at the end and you'll see most of the 80W90s are outperformed by 75/90s.
They don't show the dura blend there, but the Pennzoil 80W90 ( which has been widely substituted for the Nissan OEM Differential) is shown there and it ranks quite low.

 

Since when does conventional oil ever outperform synthetic lol?. I wonder why Nissan doesnt make their own gear oil.