Porsche Forum - Porsche Enthusiast Forums

I've an '87 Carrera with about 86K on it and have been adding what I think is a lot of oil ever since I got it. (7 years ago @ 53K miles) It now goes through about a quart every 250 miles or so. And lately, it's developed an odd smoking habit. If you come to a stop light after a 2-3 minute steady street cruise at about 3000-3500rpm, it will start to smoke after idling for 20-30 seconds. Sometimes it is just a light puff and other times it is a very noticable cloud - grey/white color and not disipating like water vapor. At one point I pulled the Cat off to see what would happen and I went about 2 miles and had to return home - I just knew I had a blown engine - the smoke was so bad. I had it looked at (by a reputable Santa Ana shop) and they didn't find anything amiss other that a little head leakage. It seems to run OK and the smoke is gone at all other times. I just had it smoged today and the tech said he found nothing wrong and that oil burning would show up on his tester. While I was at the test facility, I left it idling to keep it hot, and it started to smoke.. a lot! I then shut it off - crossed my fingers it was hot enough - and restarted it for the test. No Smoke! I has had all it's normal service and no one has mentioned bad looking plugs or other clues. I'm taking it in a couple days for something else. Is there something more I should report or look for or insist on looking at all the plugs? Thanks for any ideas,
-Bill