the best way to check if you have a problem, or anyone that thinks they have smoke coming out the exhaust.

at night get in front of some and floor it, you may see black smoke at that time,,or blue smoke hope not white smoke ,,repete this 3 or 4 times as you may just have carbon build up. after 4 times it should not smoke any more.
if you get blue snoke on start up (first start of the day that is valve seals,or valve guides letting oil leak into a cylinder, upon start up it burns)

1 blue smoke =oil
2 black smoke= fuel
3 white smoke= water

jim