Do you use 15W40 , 10W30 , or even a lighter weight oil ?

Did you use it based on some's recommendation or what the owners manual stated ?

Not asking about Syn-oils , yet............

15-40 year round. 99% of the people i know do the same

15w40 Rotella.  Been using it since I first bought a diesel. 

Summer time always have run 15w-40, Delo. This winter I switched to a 5w-40 full synthetic for the cold start flow. It gets really cold (sometimes down to -45f ambient air temp!!!) up here in Grand Forks, ND, otherwise I would just stick with the 15w-40.

15w-40 rotella since mine was new, year round. I dont see the cold temps alot of you fellas see.

15w-40 engine oils with temps as low as -20*F no issues.

I run synthetic 15w-40 year round, if I ran dino oil and saw below 0° I would switch in winter. I have seen how slow dino 15w oils move below 0, it's not something I want in my engine. If I lived in areas that saw below -25° I would run synthetic 5w-40.

 

There are a few 30wt oils that meet the Cummins min high temp cST spec, Amsoil HDD comes to mind. But if you tow heavy or make a bit of HP I would stick to a 40wt.

I run 15w-40 Rotella year round. I see -10* or colder sometimes. But most of winter is between -5* and 30*, Never have an issue.

Still flowin'

 

 

I have a hard time with the synthetic idea being all the local truckers (loggers and other wise) I running this same oil in their over the road trucks. I'm finding a very very small percentage of Over The Road truck even consider synthetic as a option. But weight wise I would adjust weights for long term exposure to minus temps. Like where I'm at I might see week or 2 weeks and pop back up again. Not worth losing sleep over it being once again these big over the road truck run the very same oil.

The over the road trucks flow a ton more oil volume through their pumps though. Not to mention the general size of their oil filters and what not. You may not be cold enough to worry about it in Idaho but I noticed a big difference when I switched to the synthetic here. The truck starts and just generally runs easier. Its nice to have almost instant oil pressure vs. waiting 10 minutes just to get up to 40 psi.

Like I said before though, Idaho doesnt really get all that cold, even -20 isnt really all that cold IMHO.

Sump size makes comparing OTR to our ISB difficult.

 

I am running dino on my new motor right now and there are some noticeable differences over synthetic. Dino takes longer to build pressure, and drops pressure with temp quicker. Synthetic is just more temperature stable.

15-40 Valvoline Premium Blue.  Lots of trucks with hundreds and hundreds of thousands of miles on them with conventional 15-40.  Brand is personal preferrence.

I've got a little 15w-40 in the freezer at -5°F, it pours pretty slow. Once it all settles back on the bottom of the jar I will take a video.

I've run 5w-40 year round since I never know where I might be and have never had an issue with oil flow in any area, in any season. But I do run sync.

Here it is.

 

As I mentioned in the video the oils are Amsoil AME 15w-40 synthetic, Valvoline Premium Blue Conventional 15w-40, and Amsoil SSO 0w-30 gas engine oil.

 

Amsoil AME has a pour point of -44°F, and a CCS Viscosity @ -20°C of 4386.

Premium Blue has a pout point of -22°F and a CCS Viscosity @ -20°C of 6500.

Amsoil SSO has a pout point of -60°F

 

You can see why one shouldn't run conventional 15w-40 at temps much below -10°F without a block heater. At -5°F the conventional flows okay, and pump-ability will be better than flow but it still took nearly 3x as long to hit the bottom of the jar vs the AME.

 

John, you still are not going to convince some of the 'die hards' that synthetic is better oil.........

Nope. Under normal operating conditions I am not sure the gain is huge, but add some extra hp, temp, or extreme low temp and they shine.

I turned the freezer down to -10F, the Dino oil took a 10 count to run all the way down the side (but dripped some down the middle at a 5 count), the synthetic poured down the side in a 3 count.

I'll stick to synthetics.

With the weather here (70 days this season starting out below zero) I am going to stick with synthetics too. Can you imagine what the gear oil is like when it gets real cold? The ring gear would just cut a groove until it started to warm up some.

Not only gear lube but I have seen older equipment that still ran straight 30 weight oils yet where when the oil plug was pulled out on a cold engine in sub zero conditions the oil was like molasses and would'nt even come out of a 3/4 to 1 inch drain hole.

I have decided that I will probably start slowing switching all of my fluids out to synthetics. Just that piece of mind of having a fluid that will instantly flow is very reassuring. I understand that others have gone over 1 million miles on dino oil but I dont think they were in extreme low temps every single day like a few of us are.