Originally Posted by hexotic

Transmission, the dealership will refuse to do. They call it lifetime fluid. Basically there are clutch packs inside this transmission that wear down and clutch material is suspended in trans fluid. Doing a flush beyond 70k gets rid of that clutch material – not recommended as the transmission may start slipping. You can do a drain and fill, but not a complete flush. If the car is above 100k, don't touch the fluid, leave it as is.

Originally Posted by brezzsent

Originally Posted by hexotic

I did it on mine at 74k miles, runs perfect. It's hard to give a straight answer since it may differ a bit from car to car and how much it has been abused or not. If you're in the 70-90k mile range, it's a good time to do it because doing it beyond that could have negative effects. That's about all I can say and you have to make the decision based on your situation.

P.S. the AT in the G does not like hard launches from stand still. Roll pulls are fine, but from a dig, would not recommend doing it too often. I'm on my second transmission, just saying lol

Originally Posted by absurd37

I have a 2009 G37 93kmiles, it’s shifting a little slow or hard I would say, is a transmsission drain and fill the move right now? I’m also having terrible mpg, on odometer it says 11.4

Originally Posted by hexotic

That's probably pushing it and would be saver to keep it as is.

Although if you have the Q1 2009 car with the 5 speed instead of 7 speed, it may have a dipstick where you can check the state of your fluid. Or add a dipstick to the 7 AT, it has the provisions for it, they just put a plug in the hole where it attaches.

Often the issue is in the valve body and changing the fluid wont solve the issues.

Originally Posted by absurd37

Thanks for replying bro, so you’re saying trans fluid drain and fill won’t be good for anything? I researched online, trans drain and fill helps benefits with shifting smoother and better mpg. Im about to do a MAF sensor and intake clean. What do you think?

Originally Posted by Jchag28

I have a 2012 g37x awd sport ,
mods I have
-hfc fast intentions
-z1 motorsports cat back exhaust touring
- afe throttlebody spacers aluminum
- z1 motorsports ported intake plenum (upper & lower)
-z1 motorsports 2.5 inch long tube cold air intakes
-no tune yet
- stock suspension still
......
Hey everyone what should be my next mods ? Staying n/a for a while to save up but I still want to upgrade to get the most out of my engine, lmk what I should do next. probably keep going performance wise

Originally Posted by Jchag28

I have a 2012 g37x awd sport ,
mods I have
-hfc fast intentions
-z1 motorsports cat back exhaust touring
- afe throttlebody spacers aluminum
- z1 motorsports ported intake plenum (upper & lower)
-z1 motorsports 2.5 inch long tube cold air intakes
-no tune yet
- stock suspension still
......
Hey everyone what should be my next mods ? Staying n/a for a while to save up but I still want to upgrade to get the most out of my engine, lmk what I should do next. probably keep going performance wise

Originally Posted by PhatherPhish

Before doing anything to add power I recommend doing some supporting mods. The engines in these cars tend to run hot. Whether your G is your daily driver or weekend toy I highly recommend installing a thermostatic engine oil cooler and an auxiliary transmission cooler in-line with the one built into the radiator. Z1, Stillen, and Mishimoto make oil cooler kits. Stillen makes a transmission cooler kit. Building your own kit will probably be cheaper. But, this isn’t an area I would personally go cheap on.



I’d take a look at the diff bushing to see if it needs to be replaced. The stock one is fluid filled and eventually will probably leak leading to the rear diff flopping around. If you see a trail of fluid or there are visible cracks in the rubber, I’d replace it. Z1, whiteline, and a few others sell solid urethane bushing kits. New diff bushings in combo with subframe bushing collars or solid subframe bushings will help tighten up the rear end and give you marginally better acceleration off the line. It’s also one of the more cost efficient mods you can do.



Look into swapping out the open rear diff for an LSD. RWD sport models came stock with an LSD so swapping one into your AWD shouldn’t be too much of an issue. I’m not sure what the details of the swap are but I know there are several people on this forum that have done it.



Like Rochester suggested sway bars are a very good upgrade. Eibach, Hotchkis, and Z1 are probably going to be the top picks.

Originally Posted by DeafJam92

late to the party, but the rwd sport model have a viscous limited slip differential, that are prone to overheating, z1 offers aftermarket lsd you can swap out but requires a full diff swap

Originally Posted by socketz67

Unfortunately, on the 7AT swapping the pumpkin with one from a 6MT or crossover year G35/7 Sport Model is not straightforward.

I have never heard that the sport model VLSD overheats, only that the vicious fluid inside of the diff eventually loses its functionality. My car is 12 years old and it still works fine.

Originally Posted by DeafJam92

depends what your throwing at it, , anything in the 400-450 + ft lbs of torque tends to get it there