Mercedes-Benz V8 engines (450, 380, 420, 500,560) are very picky about oil pressure. This is one engine that you do NOT want to get low on oil!
Two of the uglier things that can happen is for the timing chain tensioner to go slack, the chain flops around, the little plastic chain guides break up, and really bad things happen from there.
The other thing is that the cam can go dry. The cams are lubricated by a “cam oiler” system that squirts oil onto the cam lobes through a tube with little nozzles.
The early cars have an 8mm tube, which makes it even more critical than the later 10mm setup. You do not want these nozzles to sludge up! We have seen fried cams, rocker arms flung through the valve cover, bent valves, and other ugly things.
One tip from the pros — when you change oil, fill the filter canister as best you can, and then before you actually start it up, disconnect the coil wire and crank it for a short time to bring up the oil pressure before you fire it.