"It's thinner at 75*f
. Than 10w-40 is."
Whats thinner?
the 5w-40 at 75*f.
The thickness at 212*f is the same. It's not the same when cold.
Next, flow vs psi and the cushion oil provides,
ho wait I covered that with the info from bob's the oil guy.
Then their is the oil recommendation from CUMMINS.
Everyone thinks cummins is all that so why diss the oil recommendation and use a oil that is not the correct weight. You might as well just use conventional oil for a gas engine. or a 0w-20 as it will flow better.
next, winter vs summer know the difference.
And that Big C on the bottle means that Valvoline won a bid to be Cummings oil suppler.
ALL of the dino oils that are for diesels meet the same qualities as Valvoline.
the big C is marketing towards cummins owners.
5w-40 is winter oil. 15w-40 summer.
this a hoot
"At truly cold temps it gets even worse. The OP lives in North Dakota, where it gets cold in the winter. The 5w-40 has the same viscosity at -30°F (-22°F) as the 15w-40 at only -20°C (-4°F). Likewise, the synthetic 5w-40 still pours down to -39°C (-38.2°F), whereas the non-synthetic 15w-40 is done by -30°C (-22°F). If you live somewhere where it gets really cold, it's a no-brainer."
The only time it has the same vis is after the engine or the oil is up tp 212*F.
When a engine is cold the parts shrink . There are greater tolerances between the parts, a thin oil is not going to give the cushion the parts need. This allows for metal to metal contact.
and again your thin oil at 75*f is not giving the protection you think it is because you say flow is everything and it is not.
It doesn't get any colder in ND than in MN.
-60*f is the coldest each state has recorded.
and guess what sherlock we and a lot of others run 14w-40 year around and guess what those old diesels are still running. and they do start when it cold out.
Remember, the only difference between a 0W-40 and a 10W-40 is that the 0
W-40 thickens less after you turn off your engine. It is still too thick in the morning at startup but not as thick as the 10W-40. Yet, they are still too thick to use until they both warm up to operating temperature at which point they have the save viscosity, around 13 to 14. Remember that the 0W-30, 10W-30 and straight 30 grade oils all have a viscosity of around 10 at normal engine operating temperatures. They all thicken when you turn off your engine. The 10W-30 will thicken the most.
http://www.bobistheoilguy.com/motor-oil-108/
The best way to figure out what viscosity of oil you need is to drive the car in the conditions you will use. Then use the oil viscosity that gives you 10 PSI per 1,000 RPM under those circumstances. For some reason very few people are able to get this simple principal correct
The extended drain interval is not adding another 5000mi to the recommended interval it's extending it to 5000mi.
How did those old diesels last for so long with that thick nasty oil that does not lubricate at start-up?
(sarcasim)