If I was to choose between a coolant heater and a heating pad I would use a coolant heater. It is a far better heater because it heats the coolant then the metal and the heat is used 100%. The heating pad must heat itself enough to "transfer" the heat to metal then coolant. If the pad is not 100% touching the metal to transfer heat, its not heating 100%. Take it from me I know. I'm an auto/ diesel mechanic for the state of Illinois. Out of 200-300 plow trucks and 200+ state police cars we have, they all have coolant blockheaters in them. Not one of our equip. have heating pads.