RXPoison

Hey guys, I recently purchased a 1990 Rx7 GXL. Everything seems to be running decent except the abnormal smoking during startup and after higher Rpm shifting. The smoke is white. During startup, the engine will rev up automatically to around 4000RPM, blow out smoke for seconds and then go down to a normal idle. The other times are usually around 5000RPM or above, and seems to poof out the most white smoke when I change gears at that RPM. I'm thinking it could be an oil seal in the transmission, or a bad clutch, but need some help with it. Thanks.