Ok, I smell what your stepping in, Butt... I noticed this prob at the end of 2016 season spent most of the off season researching forums, all pointed to filler cap, so I checked oil filler cap couldn’t determine if it was vented or not, made a conscious decision not to poke hole through, both boat and motor are year2000 why should I change it now. So I left it alone all through 2017 season delt with oil in my in-line fuel filter and very Smokey warm-ups and no issues all season 150+hours ( after warm up smoke clears to normal and no oil in filter) So heat,expansion,pressure, pushes oil back down fuel line while at rest right , Pulled boat from slip nov 4th she sat in driveway all week temps in Rhode Island never reached above 55*F ...result oil in filter,so I winterize boat, fog engine,empty fuel tank,cover, and put to bed. Four months later 3/18/18 sunny temperature outside 28*, temp on boat under dark green tarp 74* ...result NO oil in fuel filter . What am I missing, I’m about to spend $450 on a new vro2 before something catastrophic happens. Sorry for the loooong explanation.