Ok. Next step is to change the oil/filter only filling to the 1/2 area on the dipstick, go for a nice long slow cruise (idle to 1/2 throttle with no 3/4 to full throttle operation), allow engine to cool, then take note of the oil level.
THEN.... Go for a nice long balls-to-the-wall (wide open) cruise, allow to cool and check again.
If the level rises at an idle....then falls back to where it was during high speed/heavy load use then the factory techs claim that either the piston rings have not seated yet, or the engine was not broken-in correctly.
If the oil level continues to rise regardless of how it is run then it's time to sell it and buy a 2-stroke...because you won't be willing to pay what it will take to fix it.... Or just continue to run it and change oil about as often as you trim your fingernails, or at least before it blows out the dipstick tube. Don't just drain it down because the oil is being thinned/diluted.
(So much for "clean/green running engines", right?)
Some techs are blaming the use of synthetic oil, but I'm not even gonna weigh-in on that one.
Bottom line; There is no reasonable ($$$$) repair that can be made.
All of the above is assuming that it IS FUEL and not water. If there's water in the oil then we need to troubleshoot differently.