It's a good idea to change all fluids, especially at the very first service interval. When gears, bearings, and related components wear into each other, they create impression marks into the metal surfaces they contact, this creates metal particles that get suspended into the lubricating oil. That's why the first service is the most critical, because it's the "wear-in" period for brand new parts. I think Polaris offers a lubrication kit that comes with various oils and grease.