i know this is an s2k forum but my dad has a 04 350z and when i started it up the other day i heard a slight rattle and then knocking(white/bluish smoke came out and it smelled bad). then i let it idle and it dissa- appeared. then i started it back up and it didnt knock or anything, so i backed it out of the driveway and same white smoke with a hint of blue came out and so i got to the street and put the car into nuetral and revved it and some black smoke came out. it drives fine and hasnt done it again, any ideas or suggestions?

 

So it burnt fuel, oil and coolant...

take it to nissan and get it checked.

 

might be the valve seats..could be head gasket going bad.white smoke =coolent,blue smoke=oil..

 

I heard that 350Zs have bad head gaskets BUT it could just be an urban legend. Get it checked.

 

my friend and many 350Z had a similer problem. i belive the crankshaft was the issue which led to rebuilding the short block, get it checked ASAP

 

valve seats huh?
you mean seals?

bring it to nissan or just run a compression test, and a coolant pressure test if you has low compression on a cylinder run a cylinder leak-down test

 

same, get it checked by nissan def

 

My brand new G35 had a rattle at start up. I was told the cam chain tensioner was oil pressure operated. At start up, obviously there wouldn't be any oil in the tensioner so the cam chain would make some noise for a second or two. My folks Maxima does the same thing. I don't know about the smoke though. Oil can only get into the combustion chamber two ways.