Weatherman has us all lathered up about the polar vortex. Question for those in REAL cold areas, how cold will it start without block heater? Fuel is winterized + power service white. 142,000 miles original injectors. Thank you a be safe!

 

I got mine started at 5F with no real problems, few extra cranks is all. I would recommend getting a block heater though at some point for future use, not hard to install yourself and only about $50-60

 

LOL, it depends what you mean by "cold". Cold to me in Canada, is different to cold to someone in southern California.

If you don't have a block heater and/or cord, I hope you have adequate antifreeze rating in the cooling system.

Also critical is the engine oil. Conventional 15W-40 engine oil is not good at all for below 0F /-18C cold starts. It's really thick and the engine will sound like hell until it warms up.
15W-40 synthetic is much better, Synthetic 5W-40 or syth 0W-40 is even better.
I used conventional 10w-30 for winter before but I wouldn't work the engine hard, towing, on 10W-30. Its too thin.

 

Its unofficially stated that a cold Cummins ISB can start in temperatures down as low as -20*F without the help of plugging the block heater. I would presume that is going to be dependent on battery condition too...

 

Curious...

If you have the capability of plugging in your truck, then why don't you ?

My truck will start on really cold days as well, with or without the block heater.

It starts so much smoother with the block heater, sounds better (not making a bunch of rattling diesel noises), warms up faster. When I start my truck up in very cold weather, without plugging it in, it sounds like it's gonna blow up. Noisy, smoky LOUD. None of that happens when it's been plugged in overnight.

I see no negative to plugging it in, as I believe that's why the factory put them in our trucks.

 

 

I stay inside when the temp is below 30

 

Thanks for all the replies! Do have block heater and used it, just had to jockey other cars in the AM when leaving for work. Running 5W40 syn oil , winter front, Odyssey batteries, so in theory could have started without plugging in. Miss the 2000 Dodge with the three cylinder idle, did sound like it was going to implode!

 

The 2003+ Common Rail Cummins are excellent in cold weather. Your truck should automatically go into a high idle when it's below approx. -5C/28F.

The 2004+ Cummins also have a manual high idle feature. The engine idle speed can be manually controlled with the cruise control function.
At engine idle, enable cruise control and you can manually raise and lower the engine idle speed.

On your 2006 automatic, the dealer can enable this feature in the ECM, or any aftermarket programmer can enable this.

 

I have started my Cummins 12 and 24Vs in weather down to -25F without plugging them in.
If I get the chance, I usually plug them in for an hour or two and they start much smoother.
Plugging them in all night is a waste of electricity in my eyes, anything over 3 or 4 hours is just melting the snow off the hood and making my electric bill higher.

 

My old 1st gen would start at -45* unplugged without question. I sounded horrible and I hated to do it but in an emergency, it was reliable. My 3rd gen will pull off -25 or -30* unplugged if the batteries are in good shape (batteries appear to be the limiting factor on my 3rd gen) and again, it sounds horrible and I don't like to do it. You are better off to plug them in if at all possible. It's just better on everything in the long run. I give mine 2-3 hours plugged in for anything below about +10* down to -20*. Colder than that I leave them plugged in 24/7 just in case. That big 1100lb block of iron under the hood takes a LOOOOOONG time to thaw out after a cold soak when the mercury is hiding in the bottom of the thermometer.