I had that on my old vectra sri. Take my time and the oil was fine, hit the loud pedal and take up to high revs all the time. Then after 300-350 miles I would get 'check oil'. Problem was if I rev the car hard no smoke :confused:. But by chance on a night time drive with one of mates, he flashed me over to tell me everytime i accelerated off hard, his headlights showed fine smoke coming out of my exhaust. So with that info I took my car to the family mechanic and he said he's sure one of the piston rings had gone. The car had 89000 miles on it at the time. I ran it for few more months till I had an issue where the TC would keep kicking in at 70mph and that was end of the vectra and started hunting for the coupe I got now.