Hello,
Not likely for your car to suffer from valve seat recession unless you are regularly running down the PIE at 5000rpm, at least 8 times a day !
Valve seats on Mercedes engines are hard enough to survive on unleaded, my 1976 M115 is still running fine. Mercedes recommends that the valve clearances be checked/adjusted at half the normal interval, 10000km in your M110s case.
Have a good week.

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Nachi11744