How much gasoil needed to wash a car with the Optima Steamer XD?

The fuel tank capacity of the Optima Steamer XD is 20 litres. It takes about 0,5-0,9 litres of gasoil per car wash. With one tank full of diesel we should be able to clean up to 30 cars, although the minimum level sensor of the diesel tank will go off when 15 litres of the gasoil has been consumed. This is another safety feature of the machinery.