Four stroke motorcycle engine oils with a manual transmission share the same oil between the engine and the gearbox. Furthermore, most manual transmission motorcycles have wet clutches - they are cooled and lubricated with the same oil as the engine and the transmission. 

There are additional challenges that a lubricating oil must overcome in a motorcycle, including a low volume of oil, high temperatures, high specific power, high average RPM, and so high component stresses. As well as these challenges, as cities across the world look to reduce air pollution, motorcycles are coming under increasing scrutiny, with new regulations adopted to curb emissions.