Recently purchased, has had by-the-book 7500mi oil changes, reg service, dino oil. 161k miles. Any WOT downshift, like 65-85 tonight in 2nd gear, I could see pretty thick smoke in headlights of the car behind me, like my old 123 diesel! Not sure of color because it was dark out. Also, drove the car about 140 miles today, parked it, and cranked it 3 hours later. There was vapor coming from the exhaust, which seemed odd since it was driven so long and so recently - however, it was a very humid day today, 87%. I also ran a 20-gal bottle of techron, the bigger one, to about 10 gallons of V-power, if that means anything.

Car appears to be on original head gasket, valve seals, guides, and timing chain (chain guides replaced). I have had it for a week, and have no fluid leaks visible underneath the car. It's going in Monday for a 30k service at the best indie in town, partly because they go over the whole car as a bonus on that service.

Could it just be blowing crud out, maybe amplified by the techron? Maybe running rich, caused by....?
This is the strongest motor I've ever owned. Pulls like all hell is breaking loose.....makes my C350 (268hp) feel like a 4cyl.

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL