As pointed out above, the spec sheets show the CCS at two different temperatures. The viscosity is highly non-linear at those temps, and a 5 deg C difference can make a huge difference. If the 5W-20 was CCS tested at -35 C instead of -30 C, it would probably be way over 5670 cSt that the 0W-20 measured at. I don't think you can really use CCS max/actual ratio to figure anything out when the oil is at that cold of a temperature. The test data says the 0W-20 is going to crank better at super cold temps vs the 5W-20.
0W-20 in 5W-20 Engine
- Thread starter oilnut12
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But which one has the higher base oil viscosity?
Right, but, within the 20 grade, there can be a large difference in viscosity. Ex. M1 EP 5-20 is 9.0 vis ; Supertech FS 0-20 is 7.89.
Sure, but, generally, HT/HS increases with viscosity, hence, my post #23, above.
To add ... look at the viscosity of the 0W-20 and the 5W-20 at -35C on those spec two sheets.
The 5W-20 = 9300 cSt @ -35 C. Like said above, it's way over 5670 cSt @ -35 C where the 0W-20 was CCS tested. It's also way over the SAE J300 max spec of 6200 cSt at -35 C, so obviously it can't be grades as "0W".
The 5W-20 = 4050 cSt at 5 deg C warmer (@ 30C). So the viscosity over doubled from a 5 C decrease in temperature (went from 4050 @ -30C to 9300 @ -35C). A small change in temperature down there makes a huge difference.
This is why one is rated as a "5W" and the other rated as a "0W".
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Always learn new things here… Cause it seems the playing field with the difference in 5 C degrees and the max number for each appear to level.
Here is an interesting thread that was discussed last January.
ASTM D5293 (CCS) vs. ASTM D4684 (MRV)
As I do lack deeper understanding of both ASTM D5293 and ASTM D4684 I'd highly appreciate some help. Apparently ASTM D5293 is for CCS viscosity while ASTM D4684 is for MRV/low temp. pumping viscosity. I came across a seemingly odd observation while comparing the datasheets of both Ravenol REP...
bobistheoilguy.com
Does the two spec sheets from Pennzoil show a quality increase in the base oil going to 5w-20? (compared to 0w-20) The 40 c rating viscosity is near the same.
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Two of the Ravenol oils in that other thread are 5W-30 and the other one is 5W-40. Can't really compare the 5W-40 because it obviously must have more VII which really start to effect the viscosity between -30C and -35C. They all meet the spec of a "5W" of course because they all have a viscosity less than 6,600 cSt at -30C.
But again, at those low temperatures the viscosity can change a lot with just a few degrees of temperature change. The oil's viscosity sensitivity to temperature at those temperatures could be a result of the base oil and/or the VIIs used. I would think the VI would also give a hint on how much VII is being used.
Oil #1 5W-30: @ -30C = 4,301 cSt and -35C = 14,870 cSt. VI = 165. HTHS = 3.7 cP.
Oil #2 5W-30: @ -30C = 4,740 cSt and -35C = 12,000 cSt. VI = 179. HTHS = 3.7 cP.
Oil #3 5W-40: @ -30C = 4,510 cSt and -35C = 21,300 cSt. VI = 169. HTHS = 3.9 cP.
There was a reason why SAE J300 came up with the "W" (winter) rating of the oils like they have. If someone is really concerned about cold start-ups they should look at their OM and use what's recommended for their ambient conditions, or if on the fence about super cold start-ups then just go with a 0W rated oil. The "W" rating spec is just to ensure that the engine is going to start and be adequately protected during a cold start-up. It shouldn't be uses to try and determine if one oil has better base stock, and/or better or less VIIs. IMO, the HTHS is the one spec that should be focused on because an engine spends the mass majority of it's time running with fully hot oil, and the oil's viscosity under high temp, high shear conditions can matter. Just ensure you are also using an adequate "W" rated oil for the cold start-up conditions.
Looking at the viscosity at -30C and -35C is looking through a pretty narrow tube because just a few degrees in temperature change can change the viscosity at those temperature pretty dramatically. All it's really good for is to compare cold cranking start-up and pumpability performance of super cold and thick oil. All of that has essentially been wrapped up into that "xW" part of the API rating.
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Not really. The low number is generally the viscosity of the base stock. The high number is what the polymers will change the viscosity to when hot. So 5W will change to the same flow rate as 20w when hot. And... 0W is not really zero, it is somewhere less than 5.
So "they are both 20 grade oil".
Yeah there is a lot going on in that post that's just not correct about what the winter rating means and what it does not mean. One of the most common misconceptions on this board.So "they are both 20 grade oil".
VM load matters, but the proof is in the HTHS and on the road. Still I would rather have a lower to NO'er VM in my lube in a truck that is worked. I think just pulling itself around is worked 
I went to a 10W30 in a small Ford 4 cyl as it was fuel diluting. Car runs better in all aspects, but the "step up" was due to necessity rather than being in the "thickie" camp.
I will state that is the first time I went above recommended oil grade and the engine ran better in all aspects:
lugg-ability, throttle response, quietness, and fuel mileage.
10w30 Quaker Stated Full Synthetic.
I went to a 10W30 in a small Ford 4 cyl as it was fuel diluting. Car runs better in all aspects, but the "step up" was due to necessity rather than being in the "thickie" camp.
I will state that is the first time I went above recommended oil grade and the engine ran better in all aspects:
lugg-ability, throttle response, quietness, and fuel mileage.
10w30 Quaker Stated Full Synthetic.
I think burgessdg "flow rate ... when hot" comment is a bit lost. Maybe he uses a paint viscometer - a cup with a hole in it. The other comments about base stock grade and VM action go back to the beginnings of Multi-grade "All Season" lubricants. The formulation is not so simplistic nowadays. - Ken
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OK, time to haul out my 2018 explanation again:
- Oil gets thicker as it gets colder. If you feel it necessary to test this, take a room temperature bottle of oil and pour some of it out. Now stick that oil in the freezer overnight. Pour it again.
- The number in front of the W is the rating for the oil's Winter performance. This is NOT a measure of viscosity and should not be compared with the oil's hot grade, which is what comes AFTER the W. It is a QUALIFICATION of the oil's ability to pass the CCS and MRV tests for the respective rating, which are a set of viscosity ceilings. The limits are based on 5 degree celcius intervals, offset by 5 degrees. Let's look at a SAE J300:
You can see all the Winter grades do not have qualifications for HTHS or a ceiling for hot viscosity. They instead have cold temperature limits for CCS and MRV. Rather than using an oil grade, for the which the data sheets tend to be a bit sparse, let's look at a PAO base oil, which will give us some more information.
This is Mobil Spectrasyn Plus 6 PAO, from here: https://exxonmobilchemical.ulprospe...6&e=244595&culture=en-us&u=1
First, you can see that at 100C, the oil is 5.9cSt. When we move to a lower temperature, say 40C, that viscosity increases to 30.3cSt. If we go much, much colder to -40C, which is where MRV for the 0W designation is measured, we see that the oil is now 7,400cSt, massively thicker. Moving further down the sheet we can see that Mobil chose to break-out the CCS (Cold Cranking Simulator) viscosity at multiple temperatures for this product: -25C (10W): 1,400cP -30C (5W): 2,247cP -35C (0W): 3,600cP Because, as per J300, we can see that this oil falls below the upper limit for the 0W designation (6,200cP) and its hot viscosity aligns with SAE 12, this base oil would qualify as a 0w-12.
As I mentioned previously-I have a 2018 Siverado with the 5.3. The manual calls for 0w/20 and that what it gets. Currently has 48,000 miles on it. I am on a road trip right now which went through many mountain passes-towing a 30 foot 5,000 pound travel trailer. My experience shows there is no need to second guess the manual. Do what you wish.
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