Viscosities: Mobil 1 5w30 vs 10w30?

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Well, regardless of how accurate the V vs T plots are below -10C or -15C, it still gives someone a visual of how different viscosity ratings behave with temperature in a general sense. Most people have no idea how the viscosity changes (very non-linearly) with temperature, especially down below 0C.

What would be interesting (I haven't seen it anywhere) is a correlation between the different "W" ratings and the corresponding viscosity for each "W" rating range (in cSt, not cP). Like said earlier, they wouldn't be rated at 0W, 5W, 10W and 20W if they didn't fall into the proper defined "W" viscosity range, and therefore highly doubt that any lower "W" rated oil's viscosity is going to cross over another higher "W" rated oil and be more viscous anywhere below 0C, regardless of how accurate the V vs T curve plotting tool is. If someone can find one, I'd like to see it.
 
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OVERKILL

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Well, regardless of how accurate the V vs T plots are below -10C or -15C, it still gives someone a visual of how different viscosity ratings behave with temperature in a general sense. Most people have no idea how the viscosity changes (very non-linearly) with temperature, especially down below 0C.

What would be interesting (I haven't seen it anywhere) is a correlation between the different "W" ratings and the corresponding viscosity for each "W" rating range (in cSt, not cP). Like said earlier, they wouldn't be rated at 0W, 5W, 10W and 20W if they didn't fall into the proper defined "W" viscosity range, and therefore highly doubt that any lower "W" rated oil's viscosity is going to cross over another higher "W" rated oil and be more viscous anywhere below 0C, regardless of how accurate the V vs T curve plotting tool is. If someone can find one, I'd like to see it.

I agree, that would be interesting.

Are you OK with the SAE grade being different in that scenario?

A 5w-20 is going to be thinner than a 0w-40 as you cross 0C and and some point they will cross back over as the 0w-40 begins to thicken less.
 
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I agree, that would be interesting.

Are you OK with the SAE grade being different in that scenario?

A 5w-20 is going to be thinner than a 0w-40 as you cross 0C and and some point they will cross back over as the 0w-40 begins to thicken less.
I'm specifically talking about comparing 0W-xx, 5W-xx, 10W-xx and 20W-xx, where "xx" is the same hot weight rating. When comparing different rated viscosities like 5W-20 to 0W-40 as in your example, there can obviously be cross-overs that won't be seen in the the comparisons I'm focused on as described.
 

OVERKILL

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I'm specifically talking about comparing 0W-xx, 5W-xx, 10W-xx and 20W-xx, where "xx" is the same hot weight rating. When comparing different rated viscosities like 5W-20 to 0W-40 as in your example, there can obviously be cross-overs that won't be seen in the the comparisons I'm focused on as described.

Yeah, we could also do an ILSAC 10w-30 vs a Euro 5w-30 or 0w-30, which would play out similarly, the 10w-30 would stay lighter than the other two until some point below 0C where they crossover.

Things get a bit goofy here because of the "ranges".
 
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