:agree: I use only the seadoo synthetic oil because I have easy access to a seadoo dealership. If you do not have access to this oil look for the quicksilver brand, I believe Wal-Mart carries this.
QS Premium is an Ashless oil and the Doo requires a Low Ash Oil, so, if you are going to use Quicksilver's brand, get the QS PWC, and depending on engine, (587-687) synthetic blend (silver container) or full synthetic (black container).