Subaru does not have a purple coolant. Your coolant in your 2013 should be the blue "Super Coolant." If it is any color other than blue, see your dealer ASAP. Changing from the Super Blue to another type of coolant can not only damage the engine, but void your warranty. The blue coolant is specifically designed to match the metal and gasket materials in your engine and protect it for up to 100K miles (No need to replace it at 36K). Using a different coolant could result in corrosion issues, gasket failure, and sludge formation. See your Subaru dealer for the correct fluid. Part number SOA868V9270.