This is the big roundtable discussion hehe.
Everybody has there own gig about/with oil but since you said "from Seadoo" and there are 2 different ones I'm thinking your talking about XP-S Mineral and XP-S Synthetic (there 2 hi-end ones).
To B honest, you have a carb model ski and you "don't" have to actually use the more expensive syn oil (like if you have a direct inject model). If it were me, I would seek a different outlet or resource like Amsoil or even your local Walmart (they have gals of semi-synthetic very reasonable).
Remember this (and I'm pro SeaDoo) right?
Bombardier doesn't "make" their own oil, they don't have even one refinery period. They outsource to an actual refinery that will produce the oil they want (their specs of course which are tada... secret of course b/c they don't want you to know that (ie) coffee all comes from a coffee bean!). It's a big scare game to be honest as how the Mfgr's insist you use their oil "or else!".
Not saying 1 oil isn't as good as the next, there is plenty of differences like some keep your power valves a bit cleaner than others etc.
So the debate goes on :cheers: