Comparing cold temp oil properties

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By Detroit
If I want to compare two brands of 10w30 on cold temp properties, it is easy because the CCS and MRV tests are at the same temperature. But if I want to compare oils with different front ("w") numbers, there seems to be no way and so I am left with only pour point. One oil company rep told me you could use an oil down to about 10 degrees above pour point (can't remember if it was degrees F or C). But I heard pour point is not a very good way to evaluate an oil for winter use. Also heard that CCS was not so good either because two oils could have the same CCS but one have a much lower MRV viscosity. Also that MRV reflects the extra thickening that can happen to an oil when it is cooled in a certain way (too fast or two slow, can't remembere). Someone wrote on a post several months ago that they thought you could compare CCS viscosity by doubling the CCS viscosity for every 5 degrees C lower temperature. Wonder if that is true and whether there is such a simple rule of thumb for MRV? Look at these two oils. They both look the same on pour point, but how to compare CCS and MRV? oil 1: Valvoline Durablend 15w40 Pour point: -36C CCS: 5700 @ -20C MRV: 17000 @ -25C Oil 2: Valvoline Maxlife 10w40 Pour point: -36 CCS: 7000 @ -25 MRV: 21,000 @ -30C
 
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Greece
I would say that since in durablend they don't list CCS at -25C and MVR at -30C , it is way thicker in these temperatures compared to the maxlife.
 
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Paul, what you're seeing there is that even though both oils have a -36 pour point, the Maxlife 10-40 qualifies as a 10W and will hence, pump at -25C maxing out at -30C whereas the Durablend 15w-40 will pump at -20C and max out at -25C, but will probably be a block of ice at -30C. From what I can see, all you can go by the is the W number. If an oil is rated at 10W it's safe to -25 to -30C regardless of PP with the exception that there is 'some' added leeway for synthetics.
 

TallPaul

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Thanks Dr T., What you say is right on. So there is a minimum standard for each W number to ensure that W number performs down to that temp. But for a given W number one oil may have a lower MRV viscosity than another at the same temp. So when a 15W-xx surpasses the standard for 15W, how do you know how much it surpasses it by? Obviously the upper limit is the minimum standard for a 10W because if the 15W surpassed that it would not be a 15W but a 10W. Still there is no way to compare say if a given 15W is halfway to being a 10W or what. And I know the 15W oils can vary quite a bit. Valvoline All-Climiate 15w40 has a pour of -27C, whereas the same grade in Durablend has a pour of -36. I suspect the Durablend 15w40 is a good bit of the way toward the 10w minimum requirement, but how far? One fourth, One half ??? No way to calculate.
 

Patman

Staff member
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quote:
Originally posted by TallPaul: Thanks Dr T., What you say is right on. So there is a minimum standard for each W number to ensure that W number performs down to that temp. But for a given W number one oil may have a lower MRV viscosity than another at the same temp. So when a 15W-xx surpasses the standard for 15W, how do you know how much it surpasses it by? Obviously the upper limit is the minimum standard for a 10W because if the 15W surpassed that it would not be a 15W but a 10W.
To add to the confusion though, some 15w40s could actually be 10w40s. There is nothing against the rules which says an oil maker must rate their oil at it's lowest point, in other words if it passes the 10w test, they can legally label it 15w or 20w if they wish. We've read on here that Schaeffer Oil's 15w40 is in fact able to qualify as a 10w40, but since 15w40 is a very popular viscosity for the market that oil caters to, they keep it labelled as such.
 
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quote:
Originally posted by Patman: [QUOTE]To add to the confusion though, some 15w40s could actually be 10w40s.
IF they do this it MUST conform to the higher HTHS requirements of a 15w-40 over a 10w-40. Dave
 
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