On the gap cap of each Ski-Doo snowmobile you will find the recommended type of fuel for that specific snowmobile. Generally, you will not damage your sled by using readily-available automotive fuel as long as it is of at least 87-octane and does not contain more than 10% ethanol. Avoid using E-15 or E-85 as they will damage the engine of any recreational vehicle. That said, many high-performance snowmobiles specify the use of 91-octane non-oxygenated fuel for best performance. Generally, the use of oxygenated fuel is not a problem but leaving this fuel in the machine for more than 30 days can create a problem. Make it a practice, try to only use the fuel specified on the fuel cap of the machine, but occasional use of the automotive 87-octane fuel is not going to cause damage, it just reduces performance. As a rule try to use the higher-octane fuel and non-oxygenated (non-ethanol) to meet the requirements on the fuel cap.