Yeah i live in MN, and in the manual it says you can run it. I can really notice the difference when i don't get to plug it in.

 

Thank you for every reply on the subject. Yeah, SC is not cold but in the past few weeks , every morning arround 5:30 when I have to leave to work it got pretty cold, in the low 20's. I know Cummins has a good reputation but it doesn't keep me from driving slow until the engine warms up a bit. I hope I made a good choice using 5W40 Syntetic Rottella. It has a good price at the local Walmart or Autozone. I'm still using a K&N oil filter for now until I find a better one. This one is easy to replace it when the time comes. I change oil and filter every 3 Mo or 4000 miles whichever comes first. Seems like a good time/mileage interval to me, not a lot of idling time. Don't use any additives yet, but I'm thinking to. Need to find a good affordable one. 2006 Quad SLT 2500 4X4 5.9L, Patriot Blue, Stock, even the tires. Need to change them in about 8K miles.

 

I haven't done an oil analysis on the synthetic Rotella T yet, but I will in a couple months when I change it. I'll post the results.

 

I'm not slamming you, but 20* is not that cold. I ran 15w40 for 2 years and we see 0* to 35* all winter. I didn't like starting the engine at 0* but according to oil analysis it didn't hurt it. I now run Rotella 5w40 all year. Yes the engine starts easier and it seems smoother with the 5w40. And, Rotella is available everywhere.

 

It's a little colder up here even yet - I run Amsoil 15w40 Diesel & Marine year round up here. I don't plan on changing either. At -35 Celsius, oil pressure comes up nearly immediately.

 

Z-Man, I live in SC too and I have run the rotella 5W40 syn oil every winter since the truck was new. I also just pick up a Mopar oil filter at Walmart while I'm there. The owners manual says you can run the 5w40 syn oil in all temp ranges.

 

Festus, are you looking at a real oil pressure gauge or the stock one. The stock one just estimates from having slight pressure and engine temps.

 

I'm looking at pressure and temperature through my Commander as well. I've also done an actual pour test at those low temps in my garage with the 15w40 I use, and a conventional 5w30 oil. There is no comparison to the pour point. Amsoil flows and the conventional oil was like molasses.