0w versus 5w versus 10w

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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?

As a follow up, is there a tradeoff to better flow, with a wider spread in the numbers? For instance, 0w30 may flow better when cold, but if cold flow is unnecessary say in a hot summer climate would a 5w30 or 10w30 be superior b/c the numbers are closer together?
 
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FZ1

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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?
I think so. I use 0w-20 AFE seems quick flow and very smooth in my Camry.
 
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No practical difference.

Someone will probably mention the lower the first number, the more viscosity modifiers it has and/or the better base oil it has, but this is splitting hairs.
 
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It's not about the flow. It's about the ability to be pumped.
Yes. The only time flow is relevant is the ability to flow to the pump pickup tube without shear-induced gelling, this only happens in the immediate vicinity of the tube and is why SAE J300 was revised. After that if it can be pumped it flows.

And if you are not in subzero temperatures then a 0W, a 5W and a 10W rated oil are all guaranteed to be pumpable. If you are at -20F then you should be using either a 5W or a 0W rated oil.
 

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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?

The difference doesn't happen at the cut-off, a 0w-xx with a higher VI than a 5w-xx will be less viscous at all temperatures below 100C typically, however, contrarily, a 5w-xx with a higher VI than a 0w-xx will be less viscous at all temperatures below 100C until you hit somewhere below 0C, and then they cross over as the 0w-xx will start thickening less.

BUT, all of that is really immaterial to "flow". As long as the oil can be drawn into the pick-up of the pump, it will be forced (flow) through the engine until the relief is open on the pump, at which point some of that oil will bypass back to the feed side.

However, heavier oil has an impact of fuel economy, so using a high VI 0w-xx will yield a decrease in fuel used during warm-up, which is why lower and lower viscosity is being chased.

In performance applications, we now often see wide spread oils with higher hot viscosities like 0w-40, which will have a lesser hit on fuel economy than a 5w-40, 10w-40 or 15w-40, but still provide the requisite hot protection. We see incredibly demanding approvals issued to these oils, like Porsche A40 for example, so their performance is well-demonstrated. They are also used in many racing venues.
 
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No practical difference.

Someone will probably mention the lower the first number, the more viscosity modifiers it has and/or the better base oil it has, but this is splitting hairs.
Is that always true? Might not base oils and other factors enter into the picture?
 
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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?
Heavily depends on the vehicle.
Example 1: I just went from Idemitsu 0w20 to Mobil1 FS 5w40 in a 2006 Toyota Camry with 3.0L V6. Zero difference. Same when I ran a 15w40 in it once.
Example 2: In 2009 Tacoma 2.7L, 2009 Scion XB 2.4L, 2008 Infiniti M35, there is definitely slightly more valvetrain (and timing chain) chatter on start-up anywhere below 60F degrees. The colder it is and the higher the number before "W" - the longer the chatter lasts. The difference between oil grades becomes audible anywhere below 60F.
 
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With a few exceptions like some M1 0W's you will see if you compare PDS's that operating temp viscosity increases as the xW increases, but some will say a lower xW oil will shear sooner/more than a higher xW. I'm just saying that the xW rating tells you more than just the xW rating if that makes sense.
 
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A positive displacement oil pump begins to build pressure as soon as it starts turning no matter the VI of the oil. And BC liquids do not compress it wont take any longer or shorter time for flow to begin through oil passages. Smaller passages may have a small time differential to build pressure but just a second or two max. The differences will be friction of the flow and load placed on the pump/drive when cold.
 
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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?

As a follow up, is there a tradeoff to better flow, with a wider spread in the numbers? For instance, 0w30 may flow better when cold, but if cold flow is unnecessary say in a hot summer climate would a 5w30 or 10w30 be superior b/c the numbers are closer together?
it doesn’t make a difference.
 
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If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?

As a follow up, is there a tradeoff to better flow, with a wider spread in the numbers? For instance, 0w30 may flow better when cold, but if cold flow is unnecessary say in a hot summer climate would a 5w30 or 10w30 be superior b/c the numbers are closer together?
My unscientific experience is a higher winter rating may have a greater negative effect on fuel economy even if the HTHS and KV100 remains the same.
 
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down in the park
If you're not in sub-zero temps, does this first number make any real world difference in automobile engines?
I understand cold flow differences make the 0w flow better than 5w at a certain ultra cold temp, something like -35 degrees below 0.
Likewise, 5w flows better than 10w at something like -30.

Let's say you're living in warmer states in the CONUS, where temps never get below -20 (and rarely get that low). Is there any real world difference between using a 0w, 5w, or 10w motor oil provided the oil is within spec otherwise?

As a follow up, is there a tradeoff to better flow, with a wider spread in the numbers? For instance, 0w30 may flow better when cold, but if cold flow is unnecessary say in a hot summer climate would a 5w30 or 10w30 be superior b/c the numbers are closer together?

What you will find most often is that the viscosity index is larger for the 0W than it is for the 5W and the 10W is even lower. So even before the winter grading becomes relevant, the 0W is likely to be thinnest.

This doesn't mean the oil flows better or offers more protection but fuel consumption could be less in the warm-up phase.
 
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My unscientific experience is a higher winter rating may have a greater negative effect on fuel economy even if the HTHS and KV100 remains the same.
Unless you’re running an ASTM fuel economy test with standardized test gasoline then yes, that observation is unscientific. You could never tell the difference in every day driving with the myriad of variables.
 
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