Silkolene’s Pro 4 is an ester-based full synthetic engine oil produced using Electrosyntec Oil Technology that releases the hidden power inside the engine, offering long-term performance retention and improved protection against engine wear. The oil is specifically formulated for both street and off-road motorcycles and exceeds JASO-MA2 standards. It is available in 10W40 and 15W50 viscosities. The MSRP is $17.95 per liter, or $68.95 per four liters.