Is there not a bluish tint to the smoke? When my truck's turbo blew it's seals, it did the same thing as you describe - puff of smoke after a brief stop at a stop sign.

You can also pull the "down pipe" from the exhaust side of the turbo and inspect for a thick black goo indicating liquid oil coming from the exhaust side of the turbo.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250