I think this is how the colors of exuast smoke go:
Blue: piston rings bad
white: water getting in the cylinders
black: running to rich or burring oil
check and see it the exhaust is puffing watter drips
check the oil and see if theres just oil in it!
check the radiator level and also see if theres oil in it
check to see if your motor uses oil
(replace the head gaskets)
