Frank,  Here's the pics of my S500 (V8, 5.0L engine) with 106K miles. I use either Valvoline or Castrol 20W50.  As you recall, I used 16oz of Auto-rx and drained it after about 800miles.  It came so clean that I will not do the second treatment.  But I've added about 5oz of Auto-rx as a maintenance dose. Car uses 8.5qts of oil.   Very pleased with the Auto-rx results!  My engine is really clean including the valve covers.  The reason for this is the high oil pressure in most Mercedes: the cold pressure runs just under 6bar (88psi) and when warm about 2.5bar (37psi). The whole engine gets 'washed'.  I've just replaced both valve cover gaskets and will not take them off. So had to take a picture from the oil fill hole. Even the varnish on the lip of the oil fill was removed.