Is there any correlation between oil leakage past the valve guides and seals and plug condition in my 91 300SE? I'm definitely at the 1 quart or more per 1000 miles point but there's no oil my plugs after being in service for 2 years/12K miles. There are external leaks but nothing that leaves a puddle when parked.

Thanks,
Sixto
91 300SE
87 300SDL