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Running a 31. Yanmar 315’s. 2600 hrs. Smoking oil and burning oil. Since Last oil change burned 1-1 1/2 qts over 25-30 hours running. Engines running great and no noise or hesitation. 25 knots at 3200rpm. Tired of mosquito spraying the marina. Up at Worton Creek—what are the like ly causes in your opinion?

Not all that familiar with the Yanmar engines but I do remember reading somewhere that there was a exhaust valve oil seal problem and a updated seal was put into service.
I most likely read it on the Boat diesel forum but I can't check because I'm no longer a member.