I have 121k miles on my 2003 g35 coupe 6mt an want to change the trans fluid I bought it two weeks ago I have changed alot even the rear differential it was kinda watery I have no idea if it's been changed before or not but I have changed spark plugs am stuff an looked like they was never changed but they wasn't black

 

Yes... change the tranny fluid. I'd recommend using Nissan MTF fluid. The recommended fluid is a strange viscosity that is almost impossible to find anywhere other than from Nissan.

Changing the manual tranny fluid is not going to present a risk as it would if you had an auto that had never been serviced before.

 

People get worried if they have a bad/abused trans and the fluid is so bad and the wear is so bad that the extra friction for poor fluid is what keeps the trans going. Generally if your trans is working fine then it would be fine to change the fluid. Not to mention, a change will only get a fraction of the transmission fluid out as lots is in the converter and other parts.

I had 157k on mine when I changed the fluid. A lot more fluid came out as the engine was removed so fluid came out the TC and the trans drained pretty well. Used back valvoline - I think - and no problems, just super silky shifts.

 

^^All good information for an AT but the OP's got a 6MT lol............

 

Yes, change it. Use Nissan MTF or Redline MT85.

Nissan manual transmissions need a GL4 fluid. It's kind of a pain to find at local auto parts stores since they all seem to stock GL4/5 fluids. You don't want any GL5 fluid, it causes corrosion on certain parts inside due to additives.

 

Okay thanks for the help

 

Changing fluids on a high mileage 6 speed MT isn't a problem! Make sure you use Nissan's recommend MT fluid! Other members have used other fluids like RedLine but we've seen various results doing so...Gary

 

I had 171796 miles on my previous 06 G35 6sp manual when I traded it in.
Never changed the transmission fluid
Never fix anything that isn't broke

Telcoman

 

This is why I promptly replace all fluids in any used car I buy. Might have been owned by someone who doesn't "believe" in preventative maintenance.

Fluids break down, and should be replaced periodically. After replacing rear diff and trans fluids, I can notice an improvement in shift feeling and acceleration smoothness. Old trans fluid makes the shifts feel a little bit notchy, especially noticeable when the weather cools down in the fall.