My fuel mileage on the '82 300D has been slowly going down over the 27K miles I've driven it (without a valve adjustment) and the engine has gotten quieter. I've gone from 27.5 typical miles/gallon when I got it to about 25.5 now.

Guess that means its time for a valve adjustment on mine too!

It runs great though, no loss of power that I can tell. Do you think the most telling impact of needing a valve adjustment is the fuel mileage? I understand of course that if you let it go too long that valves might burn and it would be hard to start.

Ken300D