Well, any MB that sits over a week will tick a bit on start-up.
It is daily drivers that tick every day loudly or do it on a re-start after sitting for a few hours. That is not a normal condition of this
Ticking coming from cars that only come out on the weekend are pretty normal. Synthetic seems to make it worse.
I think synthetic bleeds by the check valve in the filter housing
after a few days.
I wouldn't worry unless your car does it every day.
Pulling the filter housing on a 500E is at least a 2 Advil job.
It is best done on a hoist but, ramps would work if you feel so inclined.
There are 3 long 6mm allen head bolts holding the housing on.
you also have to disconnect the line to the oil pressure sensor.
The valve and spring are in the back of the housing and held in by a spring clip.
Pretty basic stuff and should be ok for a D.I.Y.er.