Hi guys, my sons 04 coupe trans gasket is leaking slightly and I am wondering if ok to drain and fill fluid and new filter at same time as I know I have read some say dont drain and fill and other yes, also what is the correct fluid? Car has 218k and trans shifts perfect.

 

Fluid is Nissan Matic J (older version) or Matic S (newer version that's compatible with J). You can use either for your application, it's strongly recommended to use actual NISSAN fluid and not a generic that's matic-S/J compatible because of the specific friction modifiers Nissan uses in these trannies. I think it's almost 4 quarts for a drain/fill? Maybe one of the 5AT guys will chime in about that.

No need to replace the filter, it's a non-serviceable large sediment screen type, designed to last the life of the transmission. Fluid change interval is 30k miles for tranny fluid and if it's never been touched in 200k+ miles then expect it to be pretty thrashed, if so then plan another drain/fill in the spring. Possibly a 3rd one next summer and just keep changing it out every month (ideally every couple days but that can be expensive so most just space it out) until the fluid looks like it's the normal color again. DO NOT POWERFLUSH!!! most techs don't actually know how to use those things and you can definitely damage the transmission. Better to just space out a few drain/fills.

As for the gasket, just drain the pan, remove the pan, clean the magnets of any metallic debris, install the new gasket on the pan and torque bolts to 70 INCH/lbs You can measure out what you drain and add that amount back through the dipstick tube. Always replace the crush washer for the drain bolt and torque the drain bolt to 25 ft/lbs.

If your G didn't come with an actual DIPSTICK like some of the earlier models were notorious for then you can pick up a dipstick for the same year of 350Z and use it.

10mm to remove the hold-down bolt on the dipstick, torque it back down to 45 INCH/lbs.

 

I've been using the Idemitsu Type-J for almost a year now in my '04.5 G35 with no issues. I had about 6-7k on the Idemitsu fluid, I drained it out for shots and giggle's with my oil change last month. Fluid came out very clean. I do a lot of short trips, so I change my oil every 3,500 miles, and I think I can get by with changing the ATF every third oil change, or once a year maybe.

I've run Matic-S, Matic-J and the Idemitsu Type-J in this particular G35 (in that order) for my first drain/fills since purchased at 158k miles. Both the 'J' fluids seem to be thicker than Matic-S. This car seems to shift firmer/better with the Matic-J/Type-J compared to the Matic-S. Most notably was with the 4-5 shift when cold, which this trans is notorious for slipping, according to my local Aamco. With the Matic-S, this shift seemed kinda soft; not slipping, but with either of the 'J' fluids this didn't happen. That said, I plan on running the Type-J or Matic-J if I can get my hands on it as its discontinued, though a few retailers still have stock leftover (CZP).

I tried the Valvoline MaxLife with my first G, a '05 G35 with over 250k on it. I underfilled the trans on this car by more than 1/2 quart my first trans service, and the fluid came out with clutch material next drain/fill. No slips or hard shifts, but man did I kick myself. Got too accustomed to Honda's where you check the ATF level with the engine OFF. That said, learn from my mistake and DOUBLE check that the fluid level. With this trans, you check fluid level with the trans fully warmed up, engine idling in park on level ground (similar to domestic cars).

It takes about 4/qts to do the drain/fill on these cars. The pan is an awkward shape, definitely more fluid will come out if you completely remove the pan. I'd buy at least 5 qts. Make sure you clean the magnets and the pan out thoroughly.
Get the OEM pan gasket. It was less than $30 at my local Nissan dealer, Autozone was ~$25 for the cheapy. I'd put the car up on jackstands at all 4 corners, as it gets pretty cramped working under there (even for my scrawny behind).
Also, for some reason Nissan put RTV on the small pan bolts from the factory. New from Nissan they are hella expensive, I put a small dab of black RTV on my old bolts. 10k miles since I had the pan off, no leaks. Currently at 173k on the car.

As Cleric said, DO NOT get a flush. Just do a few drain/fills to get the fluid clean.

 

Guys thank you so much!! I am a little confused on what exact fluid to use and available, our is a 2004?

 

All of the Jatco RE5R05A transmission were originally specced to use Nissan Matic J. This fluid has been superseded by the newer variation Nissan Matic S since Nissan no longer sells the Matic J.

Matic J was a conventional/synthetic blend based fluid, Matic S is a synthetic based fluid. Matic S is technically the "recommended" fluid for the transmissions now and if you were to go down to Nissan for a drain/fill you will almost definitely be getting Matic S fluid.

Nearly every fluids manufacturer makes something that is "Matic J/S compatible" but it's strongly recommended to use the actual OEM fluid because your shift characteristics will probably change due to different friction modifiers used in the fluid.

I haven't heard of any failures with the Idemitsu Matic J compatible fluids, it's probably safe to use. Definitely stay away from other brands though, there are a LOT of horror stories about tranny slippage using aftermarket fluids.