So recently my 2013 G37 sedan journey has been feeling sluggish when accelerating. Then a few days ago when I try to apply more gas on the freeway, it revs up quite high and only slowly accelerates after about 70mph. The problem seems to appear only or mostly in the higher gears. In the video attached, just 2 days ago it started making this sound. The sound seems to come and go and is not consistent. Only happens after being on the freeway for a little while and sometimes doesn’t even make the sound. After doing some research and taking It to a shop it has something to do with my transmission. My question is will a trans fluid change make it better? Or is my trans screwed? Can it be saved? It’s currently at 84,000 miles and I’m almost sure the trans has never been serviced from the previous owner. Any info will be appreciated thank you!

EDIT: the car still runs and is driveable. Hasn’t left me stuck. No lights on the dash.

 

Touchy subject as some believe if you have not serviced the transmission at this point, leave it alone. I changed the fluid in my son's truck for the first time at 140K, and it didn't self destruct. But there are stories on the internet indicating otherwise. I personally don't understand how old broken down hydraulic fluid keeps the transmission from failing.

AT Trans cooler ? - Nissan 370Z Forum

https://precisionlubrication.com/art...ius%20equation.

"Hydraulic oil starts breaking down at around 140°F. For every 15° above 140°, the life of the oil is cut in half. Hydraulic oil life is halved at 155°F and halved again at 170°F due to the temperature dependence of oil and its reaction rate, as per the Arrhenius equation."

Personally, I would have the dealer perform a drain and fill. This platform (Oil and Transmission) runs extremely hot (early 370Z press cars were outfitted with Oil and Transmission coolers, same platform) and destroys fluids, so at 84K I'd guess the fluid in your transmission has lost most of its useful properties.

I also perform full fluid exchanges at the dealer (12 quarts with seal conditioner) and many on the internet claim these destroy the transmission as well, so maybe I'm the wrong guy to listen to...

@IPT_Trans or @BULL may be able to provide additional insight as this seems like a gray area in the auto industry.

 

Went for the 3x drain and fill and hoped for the best. Car is still running and Turned out great. My cars shifts are feeling better too. Thank you for the advice.

 

Excellent news. Drain and fill in your situation is probably safer and provides more peace of mind vs a full fluid exchange.

When was the last time you did a drain and fill on the rear diff? It's quite a bit easier than the transmission?

I used Amsoil Severe gear last time I performed a drain and fill: https://www.amsoil.com/p/amsoil-seve...gear-lube-svg/

The transmission and diff services combined with a replacement of the rear diff bushings with polyurethane units made the drivetrain feel better than new.