I have a 2000 Maxima GXE that has a few problems. The main problem is valve noise. I'm putting a quart of Marvel Myster Oil in my gas every fill up and that seems to help, except when my gas level gets low, it starts making the noise pretty badly again. I first noticed it about
20k miles ago, whenever I would climb a pretty steep hill. Now, it's a lot worse - I don't have to be climbing a hill at all. I don't hear the noise under hard acceleration though - when I start to accelerate is when it's at its worst. My "service engine soon" light was coming on and off, now it stays on. I don't know if that's realated. Also, when I first start the car, I sometimes here a knocking noise - I suspect it could be the filter I'm using (I've been going to a quick lube and don't know what they put on it). Lastly, after the car as been sitting for a long time, like overnight, whenever I first take off down my drive, it misses - I have to put it in neutral and rev it a little - it seems to help. Any ideas?Thanks!