I usually wait until it gets down to 20 degree's. It has been a real mild winter so far and I have only plug in twice.

 

No problem leaving block heater plugged in for long periods. I have a fleet of school buses that I do that on. A couple of buses are not used much, so they stay plugged in for long periods with no problems. However, you may have to change the block heater after a few years. It's a simple job and requires draining the antifreeze somewhat like changing a freeze plug. The block heater should cost less than $40.00 to replace it. It does not cycle as some people assume, since it has no bi-metallic strip in it. My own truck, I have a timer that turns the outlet receptacle on the side of my garage on at 4:00 in the morning. I leave for work at 6:00. I only need to use the block heater when the temperature remains low,10 degrees or less above zero since I pay the electric bill. I do feel that the Cummins will start below zero without a block heater, it's just easier to fire up at those temperatures

 

Thanks for the info. It has only been getting in the 30's here. I plugged it in last night and it seemed to start quicker this morning. The reason is because I can't let it warm up very long in the mornings because it's a little loud ;D and my neighbors don't like it very much.

 

I have left mine plugged in all winter for 6 years now. I do not drive everyday, sometimes a week before I go near my truck. I have replaced the heater once and the cord once. The cord was damaged by those little demons who plug it back in as I am backing down the driveway ;D<br> Seems like the cost was right around 40 dollars for the heater. I think overall keeping my precious cummins warm just incase I do need to go somewhere is worth the cost. Not to mention I feel like I am donating to DD4x4's retirment fund at the power plant!

 

I have been known to use the block heater when its 45* outside (read all this week)<br><br>Mainly because I dont have ANY time to let her warm up before I take her up over 2000 rpms<br><br>Start it, and if I am not out of earshot in 5 minutes, someone calls the cops... stupid old people neighborhood =P<br><br>but they all love dzl straight pipe =P

 

You can also use a photo electric timer like you use for outside christmas lights that goes on at dusk and off at sunrise that way won't be on all day works great and saves on power when not driving all the time.