I took my 560 into the shop and, as suspected, it was in need of the dreaded valve job. I'm having the other suggested stuff done as well. The mechanic said that the rest of the engine is clean and in good shape for another 200,000 miles. That's good news. The bad news is the hit to my wallet.

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2002 ML320 (thereby making my 560SEL my "spare).
1992 500E, pearl black, 27,000 original miles as of 7/2003.
1990 560 SEL, black pearl metallic, sweetness to drive. Fully outfitted with driving countermeasures (Beltronics radar/laser detector and Uniden BCT-12 Bear Tracker scanner).
1985 Porsche 911 meteor metalic gray, a rocket to drive.
1988 Chevy Silverado pick-up (gotta have something to drive to the rodeo!)
1978 Corvette Indy pace car for show
1971 Opel GT for sentimental reasons