Sounds to me like it's a noisy lifter/tappet/lash-adjuster. Does the M104 have hydraulic lifters/lash-adjusters? The tap, while annoying, isn't going to hurt anything since it goes away quickly when the engine is started.

You can try some Mobil-1 full synthetic for a couple thousand miles and see if it helps (Italian Tuneup does help, one of the absolute worst things you can do for a car is drive it like "Grandpa"). Some people have had success using synthetic oil to get the lifters to stop tapping, though it didn't work for me. I replaced the set in my SDL. The SL still taps when started from cold after sitting for more than 3 days. I'm not losing sleep. The SDL tapped all the time, cold or hot. That's when you know it's time for replacement.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I don't have access to the vids / audio.

Hammering on an engine will do _nothing_ to solve a mechanical problem and could make it worse. The "run it hard" is from the days of leaky / rich running carburetors.

Drive the car normally, turn it off , let it cool, pull the spark plugs. If they are white / tan, you are driving just fine.

Does this car get many short run / drive cycles? These engines tend not to like many start the motor, run a minute, shut off. My 97 C280 165 K miles ( pretty much the same engine as yours ) has a light intermittent lifter tap that I'm leaving go.

Changing oil type isn't going to help as you have tried thin / thick. There is a check valve in the lifter, when this fails to fully seal the lifter will bleed down causing too much lash. General valve train wear contributes to noise as well. Drive the car as you have been. Also, what climate are you in? 15 - 40 is kind of thick for cold climates.

couple of motors on ebay.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt