Other than sucking about 40W from your house, or wherever you have it plugged in, there's no risk of damage to your vehicle from the block heater.

You may shorten the longevity of the heater using it that long, think of a light bulb, but no harm will come to your vehicle.

I agree that I wouldn't plug it in unless I was around. My dad has told me stories about snowplows going up in flames due to block heaters. Always kind of scared me. Enough to make me cautious. If my jeep goes up in smoke, im out a jeep and probably a garage and house too.

I would certainly agree that insulation can crack but how likely it will do so in a manner to cause a short, without tripping the supply line circuit breaker, AND start a fire is a diesel fueled vehicle is debatable. In any case the only "apparent" cracking I've seen on the half dozen or so CRDs I've touched has been directly correlated with vehicles that had been driven for some time with the heater cord in its original wadded up at the factory and zip tied to the dipstick tube positions. Even then the cracking was in the secondary external rubber that holds the 3 wires together and not in the actual wire insulation.

I also plug the crd while is in the garage. And I have the garage attached, and the coldest I had in the garage was about 37F when outside were - 5F.

My vehicles get plugged in at 2100 each night and are plugged in from October until sometime in April.

An average number to remember is 10 degrees per hour........for every hour your engine is plugged in, the temp will rise inside the block approx 10 degrees. This is very important especially if you live somewhere it actually gets cold. If it's -40 out and your rig is cold soaked......yep, your engine has achieved a whopping -30 temp. Not too many diesels going to be happy about that.

Another item that can add life to your engine is adding an oil pan heating pad. This will aid in warmup time as well as get the oil flowing if it's really on the cool side.

I was thinking also to add an oil heater pad. Do you have a specific size you're using. I would have to take the armor out to measure the pan, which I hope you can help me avoid [WINKING FACE]

I use the Wolverine brand pads and the GP100 (100 watt and gets around 220 degrees plugged in) and it's size is 4"x5". I use red high temp RTV to glue it to the pan.......I install a 75 watt on the trans if you are really serious about your cold weather play!