iston King is sold exclusively online, so you no longer have to drive to the local auto parts store to pick up oil, hoping they have the right viscosity in stock. The company offers synthetic oil in 0W-20, 5W-20, 5W-30, 10W-30, and 5W-40 and conventional oil in 5W-20, 5W-30, 10W-30, 10W-40, and 15W-40 weights. $5 per quart.