I’m not sure if it will smoke if you overfill it, but it is never a good idea to over fill these engines. I know I like to keep it right around the 1/2 or 3/4 mark.

I overfilled my 225 V8 ProXS engine by 3 quarts and it actually ran 100% fine, even watching all of the engine data during break in. How did I overfill by 3 quarts? My engine came from the factory with the wrong dipstick - Merc accidently installed the V6 dipstick. My dealer who did the install, filled the 7 quarts as part of their initial fill, but the tech never looked at the dipstick I guess. They turned the boat over to me, and I honestly didn't check the oil on a brand new engine with an hour on it. So I did a 5 hour break in and then checked the oil, and flipped out when I saw the dipstick dry! So I bought more oil and kept adding until it got to the top of the stick. 3 quarts! I was freaking out how a brand new engine could consume 3 quarts of oil during break in, in 5 hours.... I later met with the dealer tech and we measured the dipstick and called Merc - they confirmed the wrong dipstick and replaced it under warranty. My dealer never paid me back for the qty (3) $12 quarts of oil that I bought from them.... But yeah, the engine actually ran fine with 10 quarts of oil for 5 hours!

The manual says liters and then equates it to quarts.