1999 Boxster white smoke from exhaust
 

Hello, this is my first post on this forum. I recently was given a 1999 Boxster with 139k miles as a gift from a friend. When I got to his house, he said that the AOS was potentially going bad and there was a little bit of smoke upon startup, but went away after about 5 seconds and I drove the car 160 miles home with no issues.

After getting home, I parked it leveled in my driveway and checked the fluids. The coolant was fine, but the oil was a bit low so I filled it to about 80% as I did not want to overfill. Light then indicated that my oil pressure was good. The next day, I started it up, and it blew thick white smoke from the exhaust for about 10 minutes straight, so I shut it off. Started it again and checked oil cap and found a strong vacuum, so I determined that I needed a new AOS.

Got the new AOS, replaced it myself, and started the car and let it idle for about 15-20 minutes to let the system cycle. Smoked like before for about 5 minutes and slowly got less and less smoke until there was none. Drove it around the block and it produced more smoke when throttling to above 3200rpm. Parked it again and checked head gasket, traced the engine block, no issues there. There was a slight (and I mean like 3 or 4 drops) trail of coolant coming down the frame by the rear passenger tire. I started it again today and there was barely any smoke upon startup, but again it produced more smoke when throttling above approx. 3200rpm. Is this a coolant issue? My next steps are to drain the system, find the slight leak and repair it before adding more coolant. Any advice or theories helps. Thanks.

Also, the engine runs very smoothly and with a lot of power. There is (from what I can tell) 0 power loss which leads me to believe the engine is in very good shape. The car is absolutely pristine besides a minor dent in the driver door, engine bay is clean, etc. Car was garage kept.

I just recently replaced my AOS.
First, it has been my observation that if I check the oil level immediately after shutting the engine down it indicates lower than it actually is. I am guessing some of the oil is still up in the engine and has not drained down to the measurement level. I believe I get my most accurate oil level measurements first thing in the AM.
Second, when I changed my AOS there was a tremendous amount of oil in the intake manifold. I spent a lot of time and shop rags wiping out the low spots in the two manifolds where oil had pooled. If you have not done so, consider opening up the intake and giving it a good cleaning.
Congratulation on getting the AOS job done. I found it to be particularly miserable. Congrats also on the car running well.