Driving my 1990 300E 2.6 yesterday, slogging around town after two days of rigorous rural interstate travel, mysterious white smoke began pouring from the exhaust while sitting at a light. No miss, no bad fluid readings. No pulsing of the exhaust flow at the tail pipe. Added a can of cleaner overnight, in case it was a fouled injector or something simple.

Started it this morning. Still smoked. Drove about 1/2 mile continuous throttle on an uphill ramp looking like Schumacher after he cooked one on the back chute...and then, voila...no smoke. 188,000 miles with regular maintenance but a little long on this oil change. Ran as good as ever the rest of the day.

Similar experiences or known diagnosis?