Snowmobile oil debates are nearly as old as the debates about sled brands themselves! Unfortunately, they’re also just as resolved. We can only suggest that you follow the OEM recommended lubricants and coolants, but we’ll also tell you why.
In regards to your specific question, BRP recommends current Ski-Doo sleds use the BRP-branded XPS oil. Shocking that they recommend their own oil, I know. But here’s the deal, hundreds if not thousands of hours of dyno time and real world testing have gone into the development of that oil (and other OEM-recommended lubricants) for their specific engines to ensure all parts of the engine receive the proper lubrication, thus resulting in maximum performance and longevity. Many of the lubricants were even developed in conjunction with the engines they’re made for.
XPS 2-Stroke Mineral Oil is specifically designed for Rotax 2-stroke engines, and can be used either as injection oil or as a premix. It’d be ideal for your needs.
For the coolant, it’s very important that use the same kind if there is any at all left in the coolant system. If you don’t know what was used before, make absolutely sure the coolant system is completely drained before adding anything new. Factory spec for your sled is (green) ethylene glycol mixed three parts antifreeze and 2 parts water. XPS Coolant (BRP #219700362) is pre-mixed for the right ratio. You can learn more at xpslubricants.com.