A transmission includes a main gearbox and a power take off unit, wherein the power take off unit can be engaged with and disengaged from the main gearbox through an engagement mechanism having at least a first position engaging the main gearbox and the power take off unit and a second position disengaging the power take off unit from the main gearbox, wherein the power take off unit is provided with at least one lubricant inlet. The engagement mechanism includes a valve member and when the engagement mechanism is positioned in its second position, the valve member blocks the lubricant inlet, thereby preventing lubricant from flowing through the lubricant inlet into the power take off unit. When the engagement mechanism is positioned in its first position, the lubricant inlet is open and lubricant can flow through the lubricant inlet into the power take off unit.