The engine and gear box formed a bolt-up single unit. At a time when many motorcycle manufacturers used a total-loss oiling systems, the new BMW engine featured a recirculating wet-sump oiling system. However, it was not a "high-pressure oil" system based on shell bearings and tight clearances that we are familiar with, but a drip feed to roller bearings. This system was used by BMW until 1969. The wet-sump system was not overly common on motorcycles until the 1970s and the arrival of Japanese motorcycles. Until then, many manufacturers had used dry sump, with an external oil-tank made of sheet-metal.