At 150 miles per quart, the process has been underway for a while. I agree when it starts the oil consumption may be unnoticeable. But when you lose a quart every 150 miles, or 3 hours of operation, the smoke is not really subtle. And the idle speed on a rod bender at that point is a constantly varying, loping kind of idle. You will know what I mean when you hear it.

And, a bent rod that has no oil burning or other symptoms will go undetected as long as there are no symptoms. In this case the originator of the thread described a pretty severe symptom. That much oil in one cylinder is about 25% of the injected fuel load at 60 mph. It interferes with engine operation then, in the one cylinder, even if it is not visually apparent in the rearview mirror. And, it really interferes at idle where it can be more than the injected fuel load. Thus the loping idle and serious smoking at idle.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)