Originally Posted by Battlebus Galacticar

If you are losing coolant all or most of the time whether the engine is overheating or not, then the two issues are probably unrelated. There are lots of hidden places where coolant will leak slowly, unnoticed and then evaporate leaving no trace. One favourite seems to be the pipe that houses the "coolant low" warning sensor / plug which develops a crack in the rubber coating (there is a steel tube inside) and fluid will leak from around there when under pressure. Another one is a faulty bleed screw before the heater matrix where fluid will squirt out under pressure. Also, a small hose from the lower part of the expansion bottle to the engine block can become chafed from rubbing on a bracket below the fuel filter. From there it will usually drip onto the gearbox housing.