Can 10w40 4 cycle oil be used in a polaris 500 that has been using PS4?

Using 10W-40 4-cycle oil in a Polaris 500 that has been using PS4 is not recommended. PS4 is a specific oil formulated for Polaris engines, offering optimal performance and protection. While 10W-40 oil may function in a pinch, it may not provide the same level of protection or meet the specific requirements of your engine. It's best to stick with the manufacturer-recommended oil for optimal performance and longevity.