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5w-40 whoops

Expat93

Expat93

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Central Florida
So, let’s just say that someone in central Florida may have boneheadedly changed the oil and all filters and put 5w-40 in a 2025 Cummins instead of the 10w-40 as prescribed. How bad is it and how quickly should the oil be changed out? Thinking to just drain and refill since the filter is effectively new.
 
Ok, been confused on this. 5w-40 is in it but in Florida it probably should have been 10w-30. Just trying to figure out if the swap out should be done immediately
 
Everyone is going to have their own opinions on oil, but I personally don’t know anyone running 10w-30.

5w-40 of various flavors run in temps from -40 to 110. Id be willing to bet it’s the factory fill on the trucks since they don’t know where each individual engine is being shipped.
 
AH64ID said:
I also ran 5w-40 year round, -30 to +115. 5w-40 provides the best protection hot and cold, at a potential cost of fuel mileage that would be really really hard to quantify.
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I was wondering under what possible conditions 10-30 would be superior, is it fuel economy?
 
raoul_duke said:
I was wondering under what possible conditions 10-30 would be superior, is it fuel economy?
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10w-30 is the “fuel efficient” option for a truck that gets used as a minivan in a warm climate. How much more efficient is probably not enough to even be measured…

5w-40 is a superior oil choice in just about every other measurable metric.
 
Trash Panda said:
10w-30 is the “fuel efficient” option for a truck that gets used as a minivan in a warm climate. How much more efficient is probably not enough to even be measured…

5w-40 is a superior oil choice in just about every other measurable metric.
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Except shear breakdown due to the viscosity modifiers used to bring the base oil up to 40w.
 
Brutal_HO said:
Except shear breakdown due to the viscosity modifiers used to bring the base oil up to 40w.
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Which is a non issue when running any quality off the shelf oil for the recommended intervals.

I have never had an oil analysis indicate shear on any concerning levels with a multitude of flavors for 5w-40.
 
Brutal_HO said:
Except shear breakdown due to the viscosity modifiers used to bring the base oil up to 40w.
Click to expand...

And the potential for more consumption when worked hard, but even that’s minimal at the oil temps these engines run at.

10w-30 has some small advantages on paper, but in reality they don’t make up for the increased hot and cold performance of 5w-40.
 
I usually follow the manufacturer recommendations in the owners manual, I figure they know more than me usually.
My truck runs quiet, hardly any valve train noise and doesn’t use any measurable oil between changes. I have no problem running 5-40 but my climate doesn’t fall below 0° where the 5-40 is recommended.
I do enjoy the less viscosity spread of 10-30 versus the 5-40 due to the extra viscosity modifiers that Brutal HO mentioned
 
dslbrnr said:
I usually follow the manufacturer recommendations in the owners manual, I figure they know more than me usually.
My truck runs quiet, hardly any valve train noise and doesn’t use any measurable oil between changes. I have no problem running 5-40 but my climate doesn’t fall below 0° where the 5-40 is recommended.
I do enjoy the less viscosity spread of 10-30 versus the 5-40 due to the extra viscosity modifiers that Brutal HO mentioned
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5-40 is a better oil in both extreme cold and heat.

To each their own though. There is a reason why most oil threads devolve into the equivalent of cats fighting.
 
Brutal_HO said:
Except shear breakdown due to the viscosity modifiers used to bring the base oil up to 40w.
Click to expand...
In the event that actually happens, you end up with a thick 30 weight hot...so pretty much the same as you would've been starting with a 30 weight.

The 10w-30s I usually see are pretty junky. I'd take Delvac 5w-40 ESP over junk 10w-30 anyday. But then there's Delo 600 ADF 10w-30 if you're worried about other things.

...But meh noack blah blah blah....
 
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