my 240 smokes

[240sx1234]

alright so I have no idea where this smoke is coming from,its a white colored smoke that is coming out the exhaust.It will only come out though when I have been driving and then let it sit for a minute,and then rev the motor or start to go.It blows white smoke out and seems to be more the longer it sits,Ive checked the oil and the level hasnt moved but and is on the curve which im pretty sure is too much,but any help would be appreciated.