I think it may be possibly piston rings going bad but I would just like a second or allot of opinions. I have a 87 N/A supra and It has white almost black smoke comming out of the exhaust but only during wide open throttle. The oddometer has 257,000 miles and I don't know if the motor was ever rebuilt. I know the head gasket is good and the blots have been torqued to the "new" setting. If you have any help please let me know.