Comparing Cold Cranking and Cold Pumping

[TallPaul]

The following quote was made in the thread, Something to Ponder:

quote:

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Originally posted by 427Z06:
Thumb rule: cP doubles every 5C drop for dinos, although, things get pretty unpredictable in this temperature region.

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Let's look at the API Engine Oil Classifications max low temp cranking viscosity in cP and degrees C:

0W: 6200 at -35
5W: 6600 at -30
10w: 7000 at -25
15w: 7000 at -20
20w: 9500 at -15

using the thumb rule we could restate it as:

0W: 1550 at -25
5W: 3300 at -25
10w: 7000 at -25
15w: 14000 at -25
20w: 38000 at -25

Now it is much easier to see the differences between the oils.

Here is an example with Valvoline Durablend SM, which includes a PCMO 15w40:

5w20: 4400 @ -30 / 2200 @ -25
5w30: 4800 @ -30 / 2200 @ -25
10w30: 6200 @ -25 / 6200 @ -25
10w40: 6200 @ -25 / 6200 @ -25
15w40: 5700 @ -20 / 11400 @ -25
20w50: 6200 @ -15 / 24800 @ -25

 

[Blue99]

Yes, the 2X viscosity increase for every -5C temp change is a handy factor for low temperature comparisons.

Esso XD-3 data sheets actually list the cP value for 2 temperatures for the 5W-30, 10W-30 & 15W-40 dino grades, and it demonstrates the 2X factor.

Per This Link the factor is 1.7 for GRP III and PAO based synthetics.

 

[Jelly]

quote:

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Originally posted by haley10:
You must be thinking GC 0W-30 vs M1 5W-30?

Gotta look at MRV, CCS and the total picture when low temps are the main concern.

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Are we overthinking all of this?

What's the viscosity of GC at 40 and 100 (Celsius)?

 

[427Z06]

quote:

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Originally posted by haley10:
You must be thinking GC 0W-30 vs M1 5W-30?

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Just for fun last month, I put some GC and M1 5w30 in my freezer set for 10F. Guess which one looked more fluid?

 

[Blue99]

GC is 12.1 cSt @ 100c with a 179 VI.

M1 5W-30 is 10.0 cSt with a 167 VI.

The viscosity/temp curves are going to cross, since GC starts out higher & has a steeper slope to the curve.

It would be interesting if someone can calculate the crossover temperature for us.

 

[427Z06]

quote:

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Originally posted by Blue99:
It would be interesting if someone can calculate the crossover temperature for us.

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Probably wouldn't be able to do it with all the non-linearities in this region.

 

[zoomzoom]

I made a pretty good table that shows viscosity vs temp for oils I used...I'll dig it up!

 

[zoomzoom]

Here:

TEMP * M1 0W-40 * GC 0W-30 * M1 0W-30 * M1 5W-30 * M1 10W-30 * M1 0W-20 * RL 5W-20
-20 * 2661.5 * 2609.0 * 1994.8 * 2225.1 * 3424.8 * 1712.7 * 2995.8
-10 * 1197.8 * 1127.1 * 872.4 * 944.7 * 1332.9 * 730.8 * 1165.3
0 * 599.3 * 546.6 * 428.3 * 452.9 * 595.7 * 352.8 * 521.4
10 * 327.6 * 291.8 * 231.3 * 240.1 * 298.3 * 188.5 * 261.8
20 * 192.9 * 168.8 * 135.3 * 138.3 * 164.1 * 109.5 * 144.5
30 * 121.0 * 104.4 * 84.6 * 85.5 * 97.6 * 68.3 * 86.3
40 * 80.0 * 68.4 * 56.0 * 56.0 * 62.0 * 45.1 * 55.0
50 * 55.4 * 47.0 * 38.8 * 38.5 * 41.6 * 31.3 * 37.0
60 * 39.8 * 33.7 * 28.1 * 27.7 * 29.2 * 22.6 * 26.1
70 * 29.7 * 25.0 * 21.0 * 20.6 * 21.4 * 17.0 * 19.2
80 * 22.7 * 19.1 * 16.2 * 15.8 * 16.1 * 13.1 * 14.5
90 * 17.8 * 15.0 * 12.8 * 12.4 * 12.5 * 10.4 * 11.3
100 * 14.3 * 12.0 * 10.3 * 10.0 * 10.0 * 8.4 * 9.1
110 * 11.7 * 9.8 * 8.5 * 8.2 * 8.1 * 6.9 * 7.4
120 * 9.8 * 8.2 * 7.1 * 6.9 * 6.7 * 5.8 * 6.1
130 * 8.2 * 6.9 * 6.0 * 5.8 * 5.7 * 5.0 * 5.2
140 * 7.0 * 5.9 * 5.2 * 5.0 * 4.9 * 4.3 * 4.4
150 * 6.1 * 5.1 * 4.5 * 4.3 * 4.2 * 3.7 * 3.9
HTHS * 3.6 * 3.6 * 3 * 3.1 * 3.2 * 2.6 * 3.3
Ratio * 1.69 * 1.43 * 1.50 * 1.40 * 1.31 * 1.43 * 1.17

 

[zoomzoom]

By the way you can caluculate these by using this calculator:

http://www.geocities.com/CapeCanaveral/3655/VI.html

 

[Brons2]

quote:

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Originally posted by 427Z06:

quote:

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Originally posted by haley10:
You must be thinking GC 0W-30 vs M1 5W-30?

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Just for fun last month, I put some GC and M1 5w30 in my freezer set for 10F. Guess which one looked more fluid?

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I'm dying to know. Which one?

 

[427Z06]

quote:

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Originally posted by Brons2:

quote:

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Originally posted by 427Z06:

quote:

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Originally posted by haley10:
You must be thinking GC 0W-30 vs M1 5W-30?

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Just for fun last month, I put some GC and M1 5w30 in my freezer set for 10F. Guess which one looked more fluid?

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I'm dying to know. Which one?

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It was close, but the M1 5w30. Correlating with zoomzoom's chart above.

 

[zoomzoom]

The interesting thing is that some 0W-xx oils will actually be thicker then 5W-xx oils at say 0C or -10C.
So if you live in the climate where you will see at the most -10C in winter time you might be better of using 5W oil since it is going to pump faster

 

[TallPaul]

quote:

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Originally posted by Blue99:
Per This Link the factor is 1.7 for GRP III and PAO based synthetics.

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Hmmm, Durablend is supposed to be roughly 30 percent Group III. So

0.7 x 2 = 1.4
0.3 x 1.7 = 0.51

So the factor for Durablend would be about 1.9, but I think the difference in the factor is within the margin of error of the Thumb Rule, so I leave it alone.

 

[427Z06]

I'm sure Terry would be disappointed if I didn't point out that the Low Temperature Pumping Viscosity, cP Max. Viscosity with No Yield Stress(MRV values) are even more important in cold weather applications.

From the ASTM website:

D5133-01 Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique

1.1 This test method was developed to measure the apparent viscosity of engine oil at low temperatures.

1.2 A shear rate of approximately 0.2 s-1 is produced at shear stresses below 100 Pa. Apparent viscosity is measured continuously as the sample is cooled at a rate of 1°C/h over the range -5 to -40°C, or to the temperature at which the viscosity exceeds 40 000 mPas (cP).

1.3 The measurements resulting from this test method are viscosity, the maximum rate of viscosity increase (Gelation Index) and the temperature at which the Gelation Index occurs.


Sorry to digress from the original discussion.

 

[TallPaul]

quote:

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Originally posted by 427Z06:
I'm sure Terry would be disappointed if I didn't point out that the Low Temperature Pumping Viscosity, cP Max. Viscosity with No Yield Stress(MRV values) are even more important in cold weather applications.

Sorry to digress from the original discussion.

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No problem. I also heard MRV is the key value but had already calculated everyting in the CCS, but implied MRV too as in the thread title (guess my thread starter post was a tad incomplete). I'll assume the Thumb Rule applies to MRV values also.

EDIT: So here is Durablend SM MRVs (in 1,000s of cP):

5w20: 16 @ -35 / 8 @ -30
5w30: 16 @ -35 / 8 @ -30
10w30: 17 @ -30 / 17 @ -30
10w40: 21 @ -30 / 21 @ -30
15w40: 17 @ -25 / 34 @ -30
20w50: 23 @ -20 / 92 @ -30

Ooooooooo!

That 20w50 looks vicious!

Guess you could call it a vicious viscous!

[ January 26, 2005, 12:52 PM: Message edited by: TallPaul ]

 

[427Z06]

quote:

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Originally posted by zoomzoom:
The interesting thing is that some 0W-xx oils will actually be thicker then 5W-xx oils at say 0C or -10C.

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Good point. Things can get very non-linear outside the 40C-to-100C region.

 

[427Z06]

Here are the stats I have for Delvac 1300S 15w40.

MRV, cP, ASTM D 4684 29,000 @ -25°C/-13F

I'd be hesistant to apply the rule of thumb in the downward direction here as you could reach the gelation point before -30C. If the oil is going to be heavily soot loaded, I would also build myself some margin of safety too.

[ January 26, 2005, 01:00 PM: Message edited by: 427Z06 ]

 

[haley10]

quote:

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Originally posted by zoomzoom:
The interesting thing is that some 0W-xx oils will actually be thicker then 5W-xx oils at say 0C or -10C.
So if you live in the climate where you will see at the most -10C in winter time you might be better of using 5W oil since it is going to pump faster

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You must be thinking GC 0W-30 vs M1 5W-30?

Gotta look at MRV, CCS and the total picture when low temps are the main concern.

 

[Dr. T]

quote:

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Originally posted by zoomzoom:
The interesting thing is that some 0W-xx oils will actually be thicker then 5W-xx oils at say 0C or -10C.
So if you live in the climate where you will see at the most -10C in winter time you might be better of using 5W oil since it is going to pump faster

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Right. That's why this pumping thing is overblown IMO. Either it pumps or it doesn't and that's all that matters.