Kinematic Viscosity of motor oils at ambient temperature

I was trying to find a graph showing 0wX products but came across this graph of 5W30 and up motor oils at ambient temperatures. The graph starts at 0 C and goes up to 30 C. Unfortunately is does not cover 0 C down to -40 C for our friends in North Dakota and Canada.

You can see the lowering in kinematic viscosity (in cSt) as the winter ratings drop from 20w to 15W, to 10W, to 5W and you could probably extrapolate to 0W. Also, you don't have to wait until -40 C to see that the viscosity of a 5W30 is much less than a 15W40 even at say 0 degrees C. Keep in mind the units are in cSt, the same units as your viscosity at 100 C where the viscosity runs from 8 to 16 cST depending on which oil you use. It’s up to you to decide if the info is applicable to your operating conditions. Enjoy.

Cold weather graph for motor oil.JPG
 
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2,120
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WA
I think they go by mrv & ccs in those regions and not cSt. ❄️

"Unfortunately is does not cover 0 C down to -40 C for our friends in North Dakota and Canada."
 
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372
Location
Scottsdale, AZ
I’d be very interested in seeing this with 0w. Always was interested as to why the standard cSt figures are 40° and 100°c. There has to be a decent period of time in winter operations where engine temps are <40° and mfgs seem to never show CSS in any of their data sheets.
 
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Location
Brittany, France
Is there that much difference between a 5w30 and a 15w40 at 0c ? On the cars i had with an oil pressure gauge, the gauge pegs just as quickly with both oils at freezing. As long as oil is pumpable and within what the owner manual allows does it really matter?
 
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2,120
Location
WA
I’d be very interested in seeing this with 0w. Always was interested as to why the standard cSt figures are 40° and 100°c. There has to be a decent period of time in winter operations where engine temps are <40° and mfgs seem to never show CSS in any of their data sheets.

from machinery lubrication:

"The kinematic viscosity in cSt at 40°C is the basis for the ISO 3448 kinematic viscosity grading system, making it the international standard. Other common kinematic viscosity systems such as Saybolt Universal Seconds (SUS) and the SAE grading system can be related to the measurement of the viscosity in cSt at either 40°C or 100°C."
 
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down in the park
Is there that much difference between a 5w30 and a 15w40 at 0c ? On the cars i had with an oil pressure gauge, the gauge pegs just as quickly with both oils at freezing. As long as oil is pumpable and within what the owner manual allows does it really matter?

it makes a couple of watts difference in work by the battery and starter, and a little bit in fuel after starting
 
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26,433
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PNW
Is there that much difference between a 5w30 and a 15w40 at 0c ? On the cars i had with an oil pressure gauge, the gauge pegs just as quickly with both oils at freezing. As long as oil is pumpable and within what the owner manual allows does it really matter?
If you look at the graph in post #1 the15-40 is around twice as thick in viscosity between those two oils at 0 deg C. SAE J300 has defined the CCS (cold crank simulator) limits as follows. If the plot went down to -35 deg C it would be more apparent.

It doesn't take much to cause the oil pump to hit pressure relief with cold oil, regardless of the oil viscosity because they are all pretty thick at 0C compared to when they are hot (100C).

Screenshot_2020-12-31 Cold Cranking Simulator Croda Lubricants.png
 
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2,120
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WA
when it comes to cold temp performance, has the technology reached a plateau?
any significant improvements in regard to mrv and ccs in the past 5 years?
sounds like pour point is not very relevant in the presence of mrv.
 
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Western S.C.
... The graph starts at 0 C and goes up to 30 C. Unfortunately is does not cover 0 C down to -40 C for our friends in North Dakota and Canada.
If that graph extended over a much wider temperature range---higher as well as lower---they'd have to resort to a logarithmic vertical axis, which would confuse certain readers.
 
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3,460
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Millbrae, CA
ccs, mrv pour point all are fro low temps you can look them up and base oil considerations on that I would put money of the ccs.

Thats what its for.
 

Snagglefoot

Thread starter
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8,317
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SE British Columbia, Canada
By all means the CCS will tell you at what temp the oil will give you a decent start. However, for most of the USA, those temperature are not of much interest. ( by the way, I’m the OP). If anything, the chart shows clearly that a 5w30 has a much lower viscosity than a 5w40 at “cold temperatures”. In some past posts some folks have insisted they would be identical.
 
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16,551
Location
Upper Midwest
By all means the CCS will tell you at what temp the oil will give you a decent start. However, for most of the USA, those temperature are not of much interest. ( by the way, I’m the OP). If anything, the chart shows clearly that a 5w30 has a much lower viscosity than a 5w40 at “cold temperatures”. In some past posts some folks have insisted they would be identical.
They shouldn't since one is a 30-grade and one is a 40-grade. More misunderstanding about what the winter rating means and what it does not mean.
 
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