Cold Viscosity: Mobil 1 5w-20 vs. GC 0w-30

[ColdCranker]

At what temperature would Mobil1 5w-20 have the same viscosity as GC 0w-30 and Mobil1 0w-40 synthetics? I see pour points, and the specs for "5w" vs. "0w", but does anyone know the full viscosity curves, from, say, -40 degF all the way up to, say, 300 degF ????
This question may be too challenging for this group, and the manufacterers won't give it out.

Reason for my question:
I'm looking to lower start-up wear with lower viscosity on frigid mornings (-20 degF worst case).
This is surprising to me: Mobil 1 5w-20 flows better at -2 degF than German Castrol (GC) Syntec 0w-30 or Mobil 1 0w-40. I tested it out after an outdoor cold soak last night in Colorado where it got down to about -6 degF outside, and was -2 degF when I poured each into test tubes to take a direct look a flow.

If you want the best oil flow down to -2 def F, then use Mobil 1 5w-20 over Castrol Syntec 0w-30 or Mobil 1 0w-40. The Mobil 1 5w-20 synthetic was flowing slightly better than the other two, despite the "0w" rating on them! I was surprised, since the "5w" part seems to imply a higher viscosity on cold days, but it doesn't in this case. Granted, if the temperature was really low, like -15 degF, then the "0w" synthetic oils might have equalled the "5w" oil, but thats getting pretty cold. In fact, I now wonder where the "equal point" is between these three oils. By that I mean what cold temperature would all 3 oils have the same viscosity? Anyway, the internal metal-to-metal scraping on a super-cold start is scary when I just put $22,000 into a new Ford Freestyle Duratec 30 engine!

 

[vad]

I think you're overcomplicating things.
The difference in the cold temp fluidity among those oils won't be significant enough to make a difference in your start-up wear rate.

 

[ColdCranker]

Maybe a shorter way to ask this would be: Has anyone ever tested the viscosity of those 3 synthetic brands/weights at around -15 degF? (The Mobil1 5w-20 won (thinnest) at -2 degF, but we actually get colder mornings in Colorado.)

 

[ColdCranker]

Replying to: "The difference in the cold temp fluidity among those oils won't be significant enough to affect your start-up wear rates. "

The 5w-20 was noticeably thinner at -2 degF. I almost agree with you, because the other two were doing OK, just not quite as thin.

 

[ColdCranker]

But the bigger concept here is: Why is a 5w- beating two 0w-'s? Would you expect that?

 

[ColdCranker]

I did notice that Pennzoil Platinum synth Hybrid 0w-20 goes to the trouble of getting a "0w-" rating when they could have just done it in 5w-. Pennzoil seems to think there is a significant difference between a 5w and a 0w.

 

[vad]

Check out this thread.

code:

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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

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quote:

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GC qualifies as a 0W-30 multigrade, per the SAE J300 viscosity chart, at 2 temperature extremes.

It is a 0W since it is less than 6200 cP at -35C and it meets the SAE 30 100C requirements at 100C.

No specifications exist as to what the temperature/viscosity curve does between these two temperatures.

The GC 0w-30 vs. M1 5W-30 viscosity anomaly exists due to the fact that GC is 12 cSt@100C and M1 5W-30 is 10.5 cSt.

Since both have high VI indexes(which is really the slope or rate of change of the temperature/viscosity curve), both are getting thicker at similar rates as the temperatures get colder.

It simply takes GC awhile to catch up to the M1 5W-30 & pass it up and be thinner on the way to the -35C final temp!

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[ColdCranker]

Small correction to last post: Not 5w-30, but should be 5w-20.

 

[ColdCranker]

Excellent data. I'm amazed you've been able to find something I've never been able to find. I'm not as good a googler as I thought!

 

[ColdCranker]

Never mind, I now see what you're saying: Ignore the "Small correction to last post: Not 5w-30, but should be 5w-20." statement above.

 

[ColdCranker]

OK, the data table above is in Celsius units, and -20 degC = -4 degF, and the numbers between Mobil1 0w-40 and GC 0w-30 match my observations. I thought the 0w-40 seemed slightly more viscous (just slightly) compared to the 0w-30.

 

[ebaker]

Note the M1 5w30 is thinner at all listed temps than M1 0w40 and GC 0w30.

 

[ColdCranker]

ebaker's point is true. I'm surprised. In fact, makes me think I should be using Pennzoil's new synthetic 0w-20, but I hate to give up hot viscosity (man, it gets thin hot) to pay for it. Maybe what I should do is use Pennzoil 0w-20 winter and Pennzoil 5w-30 summer(platinum synthetics of course).

 

[427Z06]

Nice to see my work being used.

I need to update the M1 5W-30, 10W-30 and add the 5W-20 and EP line. But the values in the above chart are still good for the comparision purposes used here.

 

[ColdCranker]

It does get to the real heart of the matter: How to combat start-up wear when its extremely cold outside, and you know you just sold your mother-in-law for that car of yours. Start-up wear is the big source of engine wear.

 

[Steve S]

The wear to really be concerned about is the time it takes for the oil to get from the sump to the pump. The time it takes for the engine to warm up and the pistons to get round etc is just the way it is.

 

[lyle]

Methinks M1 5W-30 could easily meet the "0W" requirements. At the cold end, one only has to meet a maximum cP spec, and if you're below it, you meet the requirement to be labeled a "XW". I saw a chart from Mobil Canada posted here some time ago that showed M1 5W-30 at 3600cP at -30C, while M1 0W-30 was 3900cP at -35C. Both meet the maximum cP spec for their respective ratings, and both are correctly labeled.

 

[ColdCranker]

Lyle, I agree, although, similar to what you just said, I think the M1 5w-20 would also qualify as a 0w-20. It is not in the chart above, but I chilled it to -4 degF along with M1 0w-40 and GC 0w-30 and noticed the 5w-20 was a bit thinner (just swishing it around in a test tube).

 

[GoldenRod]

ColdCranker,

I think you're equating fluidity with protection. The 5W-20 may start flowing quicker at a low temp start-up; but may not provide the necessary "cushion", as the GC 0W-30, to protect vital engine parts in motion.

 

[vad]

quote:

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Anyway, the internal metal-to-metal scraping on a super-cold start is scary when I just put $22,000 into a new Ford Freestyle Duratec 30 engine!

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It can come to a point when a thicker oil would actually protect your engine better during the first few seconds after the cold start-up since it tends to form a thicker film and doesn't drain as fast down the oil pan after the engine shutdown.