I believe the block heater is a 750 watt unit.

Still worth putting it on a timer, 3 or 4 hours is all you need. Mine is set up to kick on at 1 am, normally I leave at 5. The timer stays on until 9 (so it's warm and ready on weekends). It kicks back on at noon and runs until 3 pm, again for weekend use.

 

I only have water in there till I get back home, and the temps have been dropping to 20*. Once I get home I will see how it starts without the heater. And of course put coolant in it.