Optimax white smoke

I have a new to me 150 merc optimax that has a white smoke coming out at idle. I am using the DFI oil, I am not sure what was used prior. Could this be causing the smoke or something else? thanks.

Bad fuel/oil mix?

If it's white smoke, could it be a head gasket leaking water into the cylinder? Regardless, I don't think I would run it until you find the source.

Does it do it all the time? Or mostly at start up and goes away as it runs?

In cooler temps exhaust will appear heavier and lighter in color to me just like when you start up your pickup truck on a cold morning.

It does it all the time. I bought the boat in Oct and only had it out once before the past couple weeks. I don't think it was smoking then but not certain.

wait, don't 2-strokes all smoke? how did the boat run when you took it out? was it running ok?
if I start my boat on muffs, it smokes out the neighborhood

The key is the color of the smoke. If it's blueish grey, that's normal. Other colors could indicate problems. I'm guessing Gary is busy getting boats ready for the season. Maybe he'll jump in.

Run it on the cuff till warm. Pull all of the sparkplugs and crank it over, look for signs of moisture. Some additives will cause white smoke but lots of white smoke is normally a sign of water getting in a cylinder.