[Early_S_Man]

Scott,

This is a normal situation for any older 911 that is left to sit for months or years. Th oil level rises in the sump, and consequently, in the exhaust valve cover chamber, too ... to the point it is above the exhaust valve guide in the exhaust port. Oil seeps past the Teflon valve stem seal and up the valve guide, and drips into the port, and down into heat exchanger, ultimately collecting in the muffler. When the engine is started it takes a minute or so to heat up the muffler to the point that smoke is generated, hence the time delay.

Some people mistakenly state that the oil is leaking past rings, but oil collected in the combustion chamber would cause instantaneous smoke, not delayed by a minute or more! The 'classic' 911 'puff of smoke on startup' is the result of oil in the combustion chamber. This is not what is happening in this thread!