I've never plugged mine in here in TX. I've started mine down into the teens with no problem.

If I had the facilities to plug it in, I'd buy the plug set up and put it on a one hour timer if I knew it would be below 30 degrees that night.



If you want to plug it in to keep the heater warm, I'd just buy one of those kits that keeps the truck warm.

 

They aren't really needed until your sub zero, but they do help the truck warm up quicker, which translates to faster cab heat.

One of worst things you can do to these motors is to fire them up and just let them idle to warm up. Not only does it take forever, but your not getting complete combustion on a cold motor, and that is hard on cylinder walls and oil.

The best thing is to start it, wait about 30 seconds for full oil pressure and start driving easy until the gauge registers 140°.

Without my block heater on a 20° day my truck can take 12-15 miles for the thermostat to open and no warm air for 2-3 miles. With the block heater on for 90 minutes I get the thermostat to open in 6-8 miles and have luke warm air instantly.

 

Other than the above reasons, I want my truck warm up ASAP because it will be running on grease when the coolant temp is above 150 deg.

BTW I never though above the winter front will help to warm up in 90 mins with the block heater. Thanks for your info.

 

it gets COLD up here. I run an oil pan heater, trans pan heater, stock block heater and electric battery blankets and the winter front. I never know when I will get called out for work, so a timer is not practical. I leave mine all plugged in 24/7 all winter. Makes a diff of around 25-30 a month on the hydro bill. Well worth it! I also have the Espar fuel fired engine heater for when there is nowhere to plug in.

Oh yeah, even with the winter front and all those electric heaters, when it's actually COLD, it starts good but still takes forever and a day to build heat. Not so with the Espar. That puppy keeps it at 170°F!

 

Have you ever checked the oil pan temp after being plugged in for a day?

Cummins actually recommends not putting an oil pan heater on because it can cook your oil. I'm just not sure how much heat it would take to cook 3 gallons of oil, even if it was 40° out.

 

Oil pan heater's only a 100 watt because of that. But we never see above freezing from around mid Oct thru mid April, so I'm not worried. I don't plug it in at all until it gets down to about 0°F. I have seen the damage from a higher wattage one left plugged in when the truck was kept in a heated shop all the time. It smoked one of the rod bearings.

 

When I lived in Fairbanks, the 100W oil pan heater I ran kept the pan slightly warm to the touch at -20F temps. I did an oil change once in an unheated garage (about 10F at the time/man I hated that house!) and the oil pan heater after 6hrs probably helped it flow a bit easier, but it was barely warm on my hands, much cooler than the 125F water from the hot water heater, and not even close to being hot enough to bake. I don't plug in unless the temp is below +20F, and that's mainly for emissions and comfort purposes. I understand Cummins' intent and it works for 95% of truck buyers out there, but it simply doesn't apply when dealing with truly cold temperatures.

 

I don't know about Cummins but Caterpillar had a spec of no more than 12watts per square inch of element if it was emursed in the oil. This is to prevent coking of the oil (also the reason for allowing the turbo to cool below 300 degrees before shut down). I use a 200 watt that is attached to the side of the pan by being magnetic and using 1 pan bolt. Also Synthetic is not supposed to coke until approximatly 450 degrees F.
Jim O

 

Up here in North Texas I do use the block heater based on the forecast and next day's schedule. I do a lot of short trips, often short enough that the truck doesn't get up to operating temp in the winter. This gives it a little of a head start.

I too use the timer. That way I don't have to tip toe into the cold garage in the early morning to plug it in.