How long do I use my block heater

I have a timer on mine. 4 hours before I will start truck. have oil heater in oil pan too. I am not worried on the hard to start. I am more concerned on the cold start being hard on the engine. cold engine running at over 900 rpm's while you watch the oil pressure stay at 0 then slowly climb trying to lubricate all parts with the oil thick as molasses makes me cringe.

 

If it's below 0 , and your staying in the truck let it run... If your staying somewhere else, than the block heater will do the trick. As long as your batteries and fuel are ok.....

 

Clang,Clang, Bang,chatter, cough,smoke, puff,puff, now I'M o.k. (diesel engine talking yo ya.)

 

As someone already said, it heats the coolant up to a certain point and can not get any hotter. You simply cant hurt the engine with the block heater working. The only thing that will ever get messed up is the block heater itself if you run out of coolant, and the element is hot with no water. It will then melt.
You should also get a small charger since you have electric where you park.

 

Plug my trucks in even in summer for a short time if I'm able to electricity is cheaper than diesel.
Got an Esspar diesel fired heater on my one truck so it doesn't matter where I park I can keep the motor and cab warm without engine running. It's almost a must up here in Canada.

 

Ya espar coolant heater is a dream come true, you can even wire it too kick on heater fan in cab and heats the cab too, but only for couple hours, wouldn't work all night unless you get a espar air heater for the cab or bunk