Hi im new here, i have a nissan sentra supersaloon 95' model a/t pag naka neutral or park okey ang exhuast but driving at speel below 30kph emits a white smoke and again pag nuetral or park wla ang smoke...do u guys know the problem? oks naman ang takbo no probs...would llike to know the problem before i bring the car to service...tnxs alot. milleage is over 100thou km