88 305 does not smoke on first start up but if you are stopped at a red light for a while about 10 minutes after the startup the car leaves a big puff of blue smoke. Does not seem to smoke if I never stop. I thought maybe valve seats but I would think it would smoke at initial start up. Car has only 60,000 miles. What to look for?

 

Probably worn valve seals - nothing to worry about

 

My '91 vert started doing that after the fan went out and it over heated. The shop said that the temp sensor for the computer was fried and the thermostat was stuck open. They said the smoke was from the computer thinking that the motor was still cold and trying to compensate by running rich.

 

blue smoke is oil, black smoke is rich, white is water (in air or leaking in) so its not running rich, i go with what camaronewbie said, no biggie unless it wont pass emessions, just keep the oil full

 

ya its probly just need valve stem seals replaced

 

Doing valve seals isn't too bad, especially if you don't mind doing spark plugs. The seals can be changed without removing the heads. Use an air line adapter and thread into spark plug hole, the air pressure will keep the valve up while you remove the locks and springs. Remove old seals and isntall new.