Ok, get this: I drained the oil out of my 140Hp 4-stroke outboard last fall, changed the filter, filled it up with Dino amd it has sat since last October. It had about 80 hours of hard run time in 'er. So, I see that Amsoil has a newer 4-stroke outboard oil that's way better than regular dino. Couldn't run the dino this year knowing a much better oil is out there, so I got the Amsoil and drained out the "Fresh" oil out. Well, first about a 1/4 cup of dirty oil came out then all the the fresh oil came out into the drain pan. Hummm... Here's the interesting part: The dirty oil "kept separated" at the bottom corner of the drain pan and did not mix at all with the fresh oil ! I moved aroung the drain pan at angles and it stayed separated. Here I thought it would mix some, but no go... (By the way, I'm keeping the "fresh" oil for something else in the future...) Has anyone else seen or tried this ?