badkuk,
a compression test will tell you if your piston rings are getting loose. any talyer can do that.

if OTOH your compression test shows all your cylinders have high pressure (dunno the exact figure for a 2E engine, but it should be above 150psi or so) try adding 1 Liter of Automatic Transmission Fluid (ATF) to your engine oil. this will cause your oil seals to swell and seal if there are leaks.

(it will also safely clean your engine, much more safely than engine flush...)