Hey - I recently purchased a 2006 G35 coupe. I decided to change the transmission oil at the local mechanic. He used aftermarket transmission fluid and not the OEM Matic-S. Is this a big concern? It is to my understanding that you can't easily drain all of the new fluid. Not sure if I just leave it alone, drain/fill or completely flush. What do you all recommend? I made this change under a week ago and have not really been driving the car much. Vehicle has 59k miles.

 

You'll get lots of different opinions about this. Many people will tell you only to put matic-s in it. I put Valvoline in mine for years and have no problems but read lots of good reviews of Amsoil and Castrol as well. I've literally never put matic-s in my 06 since I bought it in 2014 with 150k on it and it has like 290k on it now. As long as your mechanic put the right kind of fluid in it that says it's suitable for use in cars requiring matic-s, I think you'll be fine. If it'll help you sleep better to put fluid that says Nissan on the bottle (made by some other oil company... probably Idemitsu), then it's easy enough to change it out. Every car and bike forum has oil threads but it's impossible to prove either way that if you use xxxxx fluid it will be ok or that if you don't use the oem recommended fluid that it won't be ok. Use whatever you want and then you can tell everybody how it turns out for you.

 

I had my transmission rebuilt about 2 or 3 years ago. Im sure the mechanic didn’t use Matic-S but my transmission has been working without any issues.