Engine ac Check your engine oil every time you refuel, and top up to the recommended level. ... Try and attend to them as soon as possible to prevent corrosion of the exposed panel/body work. ... How often should you service your car? ... Steptronic R 319000 ENGINE Six-cylinder with an extra-light magnesium crankcase FUEL CONSUMPTION 8, 6 litres/IOOkm Melanie with the new BMW 3- Series 325ianbsp;...