Every brand is different and sometimes engines from different eras are as well, for example Seadoo 587's early year yellow motors held water in the engines cases , 92 and later engines didn't, any 587-717 past 92 is self draining, 787's and 951 hold water in the engines regardless of year model.
Most Yamaha's and Kawasakis are self draining as are late model Polaris skis , early model Polaris engines held water in the cases also , the rule of thumb is if it is an upright engine from 92 and up it is usually self draining , it the cylinders are at a slant be very worried , Seadoo 787, 951, Yamaha 800's , Kawasaki Ultras fall in this category, the other rule of thumb here is it usually has to get below 25 degrees for a couple of days before you really have to worry about one freezing and busting, if you live up North winterize it properly period.
I put antifreeze in everything, period , that way I don't have to wonder , take a hose loose at the top of the head somewhere and pour in RV antifreeze till it runs out the back of the ski and it is pink, as soon as that happens stop, it has enough antifreeze in it, On Seadoo 4 tecs the engine has antifreeze in it but the exhaust is open loop cooled so I put antifreeze in the exhaust, on any ski I put antifreeze in the waterbox so it can't freeze and break the baffles .
On older Seadoos I have seen busted cases and cylinders, of 787's it pushes the cylinder out at the top where the o-ring is and that damage is a total PITA to fix if you can find someone to even tackle it. I have also seen the case coolers on the bottom of Seadoo 787 RFI skis crack and bust or and push out away from the engine , they usually don' know anything has happened till they put their ski in the water and it sinks, I have probably done three or four of those.
Here is the rub and why I put antifreeze in everything , what if the drain on the engine is clogged up and I have seen it happen a lot especially on engines that are run in the ocean , sand builds up in there and stops up the drains then it holds water regardless of what brand or year that it is.
I have been winterizing skis since the mid 1980's I have yet to have one damaged that I winterized , one more thing winterizing isn't just about freeze protection it is also about keeping the engine internals rust free over the Winter and keeping the gas in the tank and carbs stabilized , what I usually see here from the guys that don't winterize isn't usually freeze damage it is usually carb rebuilds from sitting with untreated gas in it for 6 months I usually don't see engines rusted stuck but if you don't fog your engine then you don't really care about your engine .
Winterization right now is $125.00 , a carb clean and rebuild usually runs $300.00 and I do a ton of them every year , I never do them on skis that have been properly winterized and those skis always crank and run when I go to Summerize them , those guys I rarely see in for issues , they are out riding while everyone elses ski is in the shop getting repaired.
I have some guys that keep their skis in heated garages which is all great and wonderful until we have an ice storm and you don't have power for days, then you are screwed., I have also had guys put droplights in their skis to keep them from freezing again if the power goes out you are screwed and I have seen several people melt stuff putting drop lights in their skis.
