I switched my 81 380sl from 10W30 to 20W50 early this summer to reduce the smoke puffs that were coming from my exhaust on exit ramps, based on my belief that the smoke was coming from worn valve stem guides, and using a thicker oil would reduce the leaks.

In addition, my research indicated that many MB owners with older cars had switched from the specified 10W30 to 20W50 with no problems, and that a veteran tech named Marty, who answers MB questions on Just Answer, said that he used 20W50 in his 380sl here:
http://www.justanswer.com/mercedes/6votr-mercedes-benz-380sl-type-oil-does-m-b-use.html

Well, the 20W50 did reduce the smoking on exit ramps. But now I’m wondering if it the head gasket problem I just developed could possibly be related to using 20W50 -- even though, AFAIK, the 20W50 shouldn’t have increased the pressure on the head gasket, which I replaced less than 100k miles ago.

Any opinions on this would therefore be appreciated, especially as to whether I can continue driving the car with the oil leak.

DD