2009 M35s transmission

[Bigswoop916]

Hello everyone out there in the NicoClub world. I just finally joined. Been following for a long time though. I have a 2009 Infiniti M35-S. First year of the 7spd transmission. Read about some quirks with it. Well mine has quirks. Up and down shifting at slower speeds like it doesn't have enough RPM to get to the next gear, and sometimes feels like it's slipping. I drive a lot as I am a real estate agent and just turned 130k miles. Bought the car with 88k 2 yrs ago. The transmission is considered to be "sealed", but I've heard there's still a way to drain and fill the transmission fluid. Im sure the transmission fluid has never been changed and I'm interested in knowing if it can be. I want to try and put clean oil in to see if that helps with the quirky shifting before I decide to have the damn thing rebuilt. Do any of you know if I can drain and fill the transmission fluid? Any help is much appreciated

[EdBwoy]

My experience with "sealed for life" transmissions is that they just mean you shouldn't have to go checking your oil levels often unless there's a leak or something. Honestly, how often do people check their trans dipsticks?

As much as the new units come without a dipstick, you can still fill them through an access hole on the side of the trans body - like a diff fill plug. The bottom of this hole usually corresponds to the max level of oil at a certain temperature. I did it on a Jaguar XJ8 with the 6 speed after replacing a transmission pan gasket. It's a delicate dance, yet very basic.
Here is the gist of it:

1. With the car off, most of the fluid is in the main trans body. When the engine is running, a good portion of it goes to the torque converter.
2. Trans fluid will expand when heated.
3. Just like a "conventional" trans, the level is best checked with the engine running and oil at operating temp.
   I'll reference 140 degrees F for the sake of simplicity.

Have the car level, accessible, safe, stable etc.

1. With the engine running and the fluid at 140F, open the fill port plug. You should feel the oil if you stick your finger there as it should be just below the circle.
   • If it gushes out, it was excessive. Likewise, if it is way below the hole, it needs to be topped off.
2. Use a pump (or gravity feed if you have access for it) to fill the port while the car is running until it trickles out of the hole.
3. Secure the plug back on before you shut the car off [remember point A above?]
4. Let it cool down again, and run the car until the trans fluid is 140F, then repeat #1 to check the correct level.

If you are doing a drain and fill for whatever reason, then just like a differential, I'd recommend you try to open the fill port first [remember it's best done with the car running in this case], then shut it off, and drain the fluid from the bottom.

1. With the engine off, open the fill port to the now "empty" trans and fill it with the correct fluid until it trickles from the hole.
2. Now you're ready to start the car again.
   [I'd say keep the fill port open, remember point A above]
3. The level drastically drops at the trans body, so you need to have a way to replenish the fluid fast through the fill port until it drips again.
4. ... pick up from #1 above where you are dancing around trying to achieve perfect drip at 140 deg F.
   If the trans fluid temp exceeds 150 deg F, turn off the car and let it cool down.

Now. your head is probably spinning after reading all that, and you would much rather be showing houses than looking at the underbelly of your car for a good part of your Saturday, right? The other forum had a lot of info from factory techs and enough people had issues to address, and so write ups existed - a phenomenon we don't have on the forum here.
This is what I would do:

• First thing is to check with the dealer to see if there are any service bulletins that would address your transmission behavior.
• Whether there is one or not, consider asking how much it would cost to reflash your trans computer anyway.
• Get a quote on changing the fluid as well, to see if it's worth your effort to DIY.

I'd say no. These guys are paying under $300 at the dealership: m37-m56-transmission-fluid-change-interval-t585647.html
Still motivated? Check the factory service manual HERE, section ATC especially for their recommended procedure.