Stupid Question about Mobil 0w-40 vs. 5w-30

[DriveHard]

If I take the viscosity data from the Mobil website:

0w-40
@40 = 75
@100 = 13.5

5w-30
@40 = 61.7
@100 = 11.0

If I take those values, and use ASTM D 341 to plot their viscosity all the way down to -20F, the 0W oil is never thinner than the 5W oil. This seems wrong to me. How can the oil rated as a 0W never be thinner at any cold temperature than an oil rated as a 5W? Please school me...I know I am missing something elementary.

Thanks!

Temp
(F) 0w-40 5w-30 15w-50
-20 5727.6 5580.2 18671.1
-19 5422.8 5266.5 17519.3
-18 5136.7 4973.0 16447.7
-17 4867.9 4698.3 15450.2
-16 4615.3 4441.0 14521.0
-15 4377.7 4199.9 13655.0
-14 4154.3 3973.8 12847.5
-13 3944.0 3761.8 12094.1
-12 3746.0 3562.8 11390.8
-11 3559.5 3375.9 10733.9
-10 3383.7 3200.4 10120.1
-9 3218.0 3035.4 9546.1
-8 3061.7 2880.2 9009.2
-7 2914.2 2734.2 8506.7
-6 2774.9 2596.8 8036.1
-5 2643.3 2467.4 7595.2
-4 2519.0 2345.5 7181.9
-3 2401.6 2230.6 6794.3
-2 2290.4 2122.2 6430.6
-1 2185.3 2020.0 6089.2
0 2085.8 1923.5 5768.5
1 1991.6 1832.4 5467.3
2 1902.4 1746.3 5184.0
3 1817.9 1664.9 4917.6
4 1737.7 1588.0 4667.0
5 1661.7 1515.3 4431.0
6 1589.6 1446.4 4208.8
7 1521.2 1381.2 3999.4
8 1456.2 1319.5 3802.0
9 1394.5 1261.0 3615.9
10 1335.9 1205.6 3440.3
11 1280.2 1153.0 3274.5
12 1227.2 1103.2 3118.0
13 1176.8 1055.9 2970.2
14 1128.8 1010.9 2830.5
15 1083.2 968.3 2698.4
16 1039.8 927.8 2573.5
17 998.4 889.2 2455.3
18 959.0 852.6 2343.4
19 921.4 817.8 2237.4
20 885.6 784.7 2137.0
21 851.4 753.1 2041.9
22 818.8 723.1 1951.7
23 787.7 694.5 1866.2
24 758.0 667.2 1785.1
25 729.6 641.3 1708.1
26 702.5 616.5 1634.9
27 676.6 592.9 1565.5
28 651.9 570.3 1499.5
29 628.2 548.8 1436.8
30 605.6 528.3 1377.2
31 583.9 508.7 1320.4
32 563.2 490.0 1266.5

 

[Oil Changer]

http://www.bobistheoilguy.com/forums/ubb...equ#Post3667816

 

[turboseize]

-20°F is -28°C.

If I recall correctly, the difference between a 5w and 0w is about pumpability at -35°C, so you might have to go even a tad lower.

The second point to take into consideration is that parrafines starting to flocculate at these low temperatures might change viscosity, so extrapolating viscosity at these cold temperatures simply might not work.

 

[jorton]

Nice post, refreshing. 5w-30 is made with lighter base oil.

 

[sicko]

Plotting based on two data points is not the same as actual tests at different temperatures.

M1 5w-30 is an excellent oil with excellent cold flow properties. But how does it compare to the 0w-40 at -35C?

 

[Shannow]

Originally Posted By: jorton
Nice post, refreshing. 5w-30 is made with lighter base oil.


Actually, chances are that the 0W40 is made with slightly lighter base oil than the 5W30, and has significantly more VII.

The 0W will be thinner than the 5W at -35 or 40C....it has to be to be rated 0W, in accordance with J300.

If the 5W met the viscosity requirements at -35/-40C, it MUST be labelled as a 0W.

the "W" rating is the extreme cold end performance, and is impacted by basestock, VII, and Pour Point Depresents...it's not an area where viscosity calculators and the like work. They are limited to a little below freezing.

But your observations are sound, and if you've got the time, the 0W30 versus 5w30 would be quite enlightening also.

 

[DriveHard]

I know that the calculator falls off as you approach the cloud point for a fluid, that is why I only went down to -20. It was just a surprise to me to see that the 0w was thicker at these cold temps than the 5w. I have been running 0w-40 in both my vehicles with the warm fuzzy I was getting better cold flow capability as compared to the specified 5w-30 for my truck...but it appears that is just not the case (although the difference is not that great). I will continue with my 0w-40 in my truck...but not I know the truth.

As requested. 0w-30ESP vs. 0w-30 AFE vs. 5w-30

Temp
F 0W-30 ESP 0w-30 AFE 5w-30
-20 4843.9 6417.2 5580.2
-19 4586.1 6045.3 5266.5
-18 4344.2 5698.0 4973.0
-17 4116.9 5373.5 4698.3
-16 3903.3 5070.2 4441.0
-15 3702.5 4786.5 4199.9
-14 3513.7 4521.0 3973.8
-13 3335.9 4272.4 3761.8
-12 3168.6 4039.5 3562.8
-11 3011.0 3821.2 3375.9
-10 2862.4 3616.5 3200.4
-9 2722.4 3424.5 3035.4
-8 2590.3 3244.2 2880.2
-7 2465.7 3074.8 2734.2
-6 2348.0 2915.7 2596.8
-5 2236.9 2766.1 2467.4
-4 2131.9 2625.4 2345.5
-3 2032.7 2493.0 2230.6
-2 1938.8 2368.3 2122.2
-1 1850.0 2250.9 2020.0
0 1766.0 2140.2 1923.5
1 1686.4 2035.9 1832.4
2 1611.0 1937.4 1746.3
3 1539.6 1844.6 1664.9
4 1471.9 1756.9 1588.0
5 1407.7 1674.1 1515.3
6 1346.8 1595.9 1446.4
7 1289.0 1521.9 1381.2
8 1234.1 1452.0 1319.5
9 1182.0 1385.8 1261.0
10 1132.5 1323.1 1205.6
11 1085.4 1263.8 1153.0
12 1040.6 1207.6 1103.2
13 998.1 1154.4 1055.9
14 957.6 1103.9 1010.9
15 919.0 1056.1 968.3
16 882.3 1010.6 927.8
17 847.3 967.5 889.2
18 814.0 926.6 852.6
19 782.2 887.7 817.8
20 752.0 850.7 784.7
21 723.1 815.6 753.1
22 695.5 782.2 723.1
23 669.2 750.4 694.5
24 644.1 720.2 667.2
25 620.1 691.4 641.3
26 597.2 664.0 616.5
27 575.3 637.9 592.9
28 554.4 613.0 570.3
29 534.4 589.3 548.8
30 515.2 566.6 528.3
31 496.9 545.1 508.7
32 479.4 524.5 490.0

 

[Shannow]

Originally Posted By: DriveHard
I know that the calculator falls off as you approach the cloud point for a fluid, that is why I only went down to -20. It was just a surprise to me to see that the 0w was thicker at these cold temps than the 5w. I have been running 0w-40 in both my vehicles with the warm fuzzy I was getting better cold flow capability as compared to the specified 5w-30 for my truck...but it appears that is just not the case (although the difference is not that great). I will continue with my 0w-40 in my truck...but not I know the truth.


Thanks for the calcs.

It's a good feeling when you discover something that is counter to what you first thought (or were told), and can then prove and rationalise for yourself.

As I've been lambasted for a number of times...the "W" is really only for the extreme pumpability temperatures, not for comparison at "normal" starting temperatures.

 

[Oil Changer]

You are getting excellent cold flow properties...for a 40-grade oil. Don't you think it's natural to expect a 40-grade oil to be heavier than a 30-grade oil? M1 0W-40 is an excellent cold weather performer.

Look at your numbers at zero:

0 2085.8 1923.5

Your numbers have merit but start to fall apart below zero. And it doesn't get that cold where you live making this rudimentary.

 

[OVERKILL]

The visc calculator doesn't work below 0C.

You'll want to extrapolate CCS and/or MRV backwards to get your cold temp performance, which will be contrary to what you've found using the calc.

We've seen this being relatively accurate to as "high" as -15C (halving up from the CCS/MRV point) in PDS's over the years.

 

[OVERKILL]

See this thread, which has an example PDS in it showing CCS halving as the temp rises:
https://bobistheoilguy.com/forums/ubbthreads.php/topics/3523922/1

For example, let's take two oils that are both 20 weights and Mobil provides us with CCS data points for both of them :

Mobil Super Synthetic 0w-20:
@40C: 44.9
@100C: 8.6
CCS: 5670@-35°C
MRV: 26,800@-40°C

Mobil Super Synthetic 5w-20:
@40C: 49.6
@100C: 8.8
CCS: 4670@-30°C
MRV: 13,200@-35°C


Oil: 0w-20/5w-20 (CCS in cP)
-35C 5,670/9,340
-30C 2,835/4,670
-25C 1,417/2,335
-20C 708/1,168
-15C 354/584


Of course the gap narrows as they approach 0C.