Try adding a couple of quarts of kerosene or Diesel fuel to the oil, enough to bring the oil level about 2" above the full mark. Then run the engine at a fast idle (1200-1500 RPM) for about 15 minutes, with no load on the engine. Drain the crankcase and change the filter while the engine is hot, and refill with straight HD-30 oil. It can't hurt, and you just might de-carbon the ring grooves enough to get a better seal against the cylinder walls.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!