Originally Posted by gasongasoff

Thanks to everyone who responded, including the peanut gallery. Sounds like other ppl have the same problem, and haven't needed an engine replacement, but I think I'll ask about it the next time I bring the car in. There have been a number of reports where the preferential LEFT-sided soot buildup was actually a symptom of scoring in one of the cylinders, which required replacement of the entire engine. Perhaps it's just a coincidence, perhaps not...