Oil supply system for an internal combustion engine, whereby an internal oil pan is arranged in the internal combustion engine, whereby the oil supply system has an additional external oil reservoir which is arranged outside the internal combustion engine compared to the internal oil pan of the internal combustion engine, whereby a supply line to be connected to the internal combustion engine is provided, which leads to a filling opening of the oil reservoir, and whereby a return line to be connected to the internal combustion engine is provided, through which oil can be returned from the oil reservoir to the internal combustion engine, whereby the return line is connected to the oil reservoir and whereby the oil reservoir has at least one oil tank, whereby a removal opening of the return line is arranged near or in the base of the at least one oil tank.