I just got done changing my Transmission and Rear Diff. fluid in my 2003 350z. This car has 22,000 miles on it, an LSD, and 6-spd manual gear box and thus far has been in good condition. I did have the standard 03' 3rd gear grinding when it's cold thing.

I chose to use royal purple's max gear 75w-90 fluid in both my transmission and my rear diff and now all of a sudden EVERY shift I make into 3rd and 4th grinds. What in the holy blue hell did I do? I just paid over 100 dollars for fluid that seemingly made my tranny worse.

Any suggestions as to a fluid change or I was actually thinking a quart of lucas trans fix fluid would help out.

 

“Best transmission fluid” and “best differential fluid” are common subjects in the Engine & Drive train forum.

 

Seriously dude? I'm not asking what the best ones are I'm asking if anyone has any ideas on how I get this to be slightly better AFTER the fact. I figured I would get the most hits on the general forum not get redirected like I'm some ******* asking what weight motor oil our cars take.

 

Hmmm, I run Royal Purple in my tranny and pumpkin, no problem at all, actuality better shifting especially in the winter months. I have also NEVER had the 3rd gear grinding, maybe it is a known issue with the 03 models.

Keep us posted on the solution, not the original problem that you have before changing your fluids.

 

Yeah idk I'm gonna give it a day or so and if there's still no change, I'll probably try syncro mesh or something. just drain out a quart and replace with that stuff. The 03' is know for the grinding though, yeah.

 

I would go with Amsoil, new Redline formula, or OEM. Only thing I like Royal Purple for, is that they put together Forum WarZ.

 

Isnt Royal Purple GL-4 and arent we supposed to use GL-3 in our trannys, like Redline?

I might be wrong.

 

motul 90-pa in the diff , and redline mtl in the gear box for 5k now..no prob and smoother days by days

 

contact Royal Purple to see if what you used was the right thing

a bad synchro is a bad synchro - a fluid change is unlikely to magically fix a bad part

 

there were quite a few threads on here about the tranny fluid and the added notchiness after switching from one to another. seems like regardless of fluid, people's experiences after switching have been some good some bad. nissans oem mtf seems to work well for many people w/the 6speed, myself included.

why are you changing tranny+diff fluid at 22k, do you track?

 

I run Royal Purple in both my Diff/Gear box and I noticed just a slight improvement.

 

The '03s were known for tranny issues like that. Did you recently purchase it from a dealer who might still have a powertrain warranty on it (like FMN)? Did you change it yourself or pay a shop to do it? Does it always grind or only when it's cold/warm? Any issues with the diff?

I would see what happens in coming days and then go from there.

 

I have a 2003 with 90K miles and finally had the Trans and Diff fluid replace. I was gonna do it myself and use aftermarket stuff like Royal Purple or Amsoil, but after calling the dealer I was informed that Nissan uses their own stuff called Nissan J-Fluid or something along those lines. Don't know if that true or not, but I decided to just take it in and have them do it, and my car runs much better now. I had my trans replaced under recall around 40k miles though. I was having some grinding issues that went away after the service.

 

So, you used a gear oil designed for hypoid gears that's the wrong viscosity for a manual transmission with known shifting problems which requires a GL-4 75W-85 oil? I'm not surprised it isn't the bees knees. You might search the interwebs for actual GL-4 transmission oils from companies like Amsoil, Redline, Silkolene, and Castrol which meet Nissan's specs. Or, just use Nissan's MTF oil.

Will

 

Thanks for the info guys. To update, I drove it all day yesterday and the grinding has actually gone away. The reason I changed it at such a low mileage was because the car is still almost 8 yrs old. I purchased it from a widow who's husband had it sitting for a long time. Just figured maybe it needed some fresh fluids. Either way I think my next change is going to be with redline mtl and mt90 mix as for the diff I've heard mixed things about different oils so I'm not sure where I lean on that.

Summit racing hq is about a 30 min drive up the highway from me so I'll be stopping up there to pick some redline up for the next change. And no, other than a few autocross events just for fun I have not tracked the car.

 

I think the updated tranny is in my future though. I haven't looked but I'm wondering how much updating the syncros in my existing one vs getting a new one would be. I would almost feel better about opening the thing up and updating the syncros just to know what I'm dealing with in there.