Thanks for the ideas, tkd_M119! Your gasket suggestion is useful given my desire to simply restore "as new" condition.
Your other two recommendations--adding "Dynamat" (by the way, what is it and how would one apply/install it were one so inclined?) and/or using different tires--modify the original design and are less appealing to me--though others may want to give these ideas a try.
For the record, as regards tires, I have tried other brands over the years (Continentals and Dunlops, though not Yokohamas) and have returned to the MXV4's. The Michelins simply provide a level of winter handling the others I tried did not.
As for gaskets, can my existing ones be treated/reconditioned, or is replacement the only way to go?
Thanks again for any help or additional suggestions.
1991 560SEL-Euro (145,000 miles)
1989 420SEL (Retired at 325,000 miles)