On my 1980 240D, I went the first 75000 miles of my ownership without adjusting the valves. The car was hard to start when below 10 degrees. Last year about this time, I adjusted the valves and found 3 of the intake valves snug (no clearance) and one with only 0.002 inches of clearance. All of the exhausts were tighter than spec but none with no clearance.

I then drove the car about a year (and 15000miles) and today I adjusted the valves again. Much to my surprise, all of the valves were within 0.001 inches of the set point last year (0.012 inch on the exhaust and 0.004 inch on the intake).

The car has seen mostly highway miles. I don't know if this is normal or not but it tends to support those out there who adjust the valves less often that the recommended maintanance interval of 15000 miles.

I think I will stop checking them every 15000 miles, and go for at least 30000.

Just some data for those interested.

Joe