I have a 92 GMC Sierra that blows a white/blueish smoke out of the tailpipes just when 1st started then it stops. It started somewhere within a week after buying it. I changed the radiator(old one was cracked) changed the oil and filter/ Had it straight piped from the cat back, tune up, and ran some lucas through it. A mechanic friend of mine told me it was from the new exhaust and that it would subside. The truck is a 4.3 v6 and runs very strong with 158k on it. I read white can be radiator coolant(which I just changed the radiator) blue is oil(just had oil changed) so I am nervous now hoping its nothing major and just the new pipes but how long will it take for it to go away? Thanks for and advise.
