Different rvp
HPL SAE 40 PCMO
- Thread starter Hohn
- Start date
I though the gasoline has 10% ethanol by default. At least around here is like that. So, I assume where I live there is winter blend all-year-round. It's understandable - ethanol is cheaper than gasoline. When I fill up - 1 gallon of my tank is ethanol.
I thought 10% ethanol was the normal limit and blenders get a waiver to go to 15% in winter months?
See other comment below ... at one time there was no ethanol in gasoline. Then they started just blending it with 10% ethanol for the winter months here ... I think that's where the term "winter blend" originated from. As summer approached they would go back to pure gasoline. The stickers on the gas pumps showed the dates when the 10% ethanol started and ended. Now they sticker just shows it always has 10% ethanol.
Could be depending on where you live. Here they started using 10% ethanol year round decades ago (high population area) to reduce emissions all year round. You can still find a hand full of gas stations that have one pump with non-ethanol gasoline, and of course it costs even more.
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The off label ethanol content has been a thing since “gasohol” in the early 1980s.
Fuel in most of the USA can have up to 10% ethanol and just be considered “gasoline.” Only above 10% is any disclosure required.
Fuel in most of the USA can have up to 10% ethanol and just be considered “gasoline.” Only above 10% is any disclosure required.
Looking through some past data for the mpg-for-OCI, I noted that on the Valvoline Restore and Protect 5w-30 run, the OCI-level mpg of 29.0 was attained at only 1500 miles.
In other words, my duty cycle was consistent enough that the OCI-average-mpg did not change from 1500 miles to the 4500 miles at the end of the OCI. It had fully converged to its long term average at only 1500 miles.
And since that prior Valvoline Restore and Protect run (about this time last year) was from Feb-Aug last year, it's quite representative of both duty cycle as well fuel grades, weather conditions, etc as my current SAE 40 run.
Which I think makes it even more notable that the monograde is stabilizing already at a higher MPG than the 5w-30 Valvoline Restore and Protect run, even though the monograde has not yet benefited at all from summer fuel and/or warmer temperatures.
Looking through my past conversation with the virtual "Dr Rudnick" helps shed light on why the monograde is seeming capable of lower traction than even the 5w-30 Valvoline Restore and Protect:
I never would have guessed the monograde would already show some significant evidence of improving on even what the 5w-30 Valvoline Restore and Protect did, but here we are.
In other words, my duty cycle was consistent enough that the OCI-average-mpg did not change from 1500 miles to the 4500 miles at the end of the OCI. It had fully converged to its long term average at only 1500 miles.
And since that prior Valvoline Restore and Protect run (about this time last year) was from Feb-Aug last year, it's quite representative of both duty cycle as well fuel grades, weather conditions, etc as my current SAE 40 run.
Which I think makes it even more notable that the monograde is stabilizing already at a higher MPG than the 5w-30 Valvoline Restore and Protect run, even though the monograde has not yet benefited at all from summer fuel and/or warmer temperatures.
Looking through my past conversation with the virtual "Dr Rudnick" helps shed light on why the monograde is seeming capable of lower traction than even the 5w-30 Valvoline Restore and Protect:
- I don't have a ton of very cold starts where the monograde disadvantage is worst.
- The Honda K20c4 is a fast-warming engine.
- I generally do not wind this engine out or run it in high-shear regimes. So the higher HTHS of the monograde isn't much of a drag penalty
- At low shear rates, the lack of VII in the monograde effectively produce less traction than what the 5w-30 Valvoline Restore and Protect had because of the relatively higher amount of VII in that oil.
I never would have guessed the monograde would already show some significant evidence of improving on even what the 5w-30 Valvoline Restore and Protect did, but here we are.
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It's just one man's insatiable curiosity asking a lot of questions that start with: "Hmm, I wonder.."I wish you'd stop posting about all this, it's got me questioning my choice of oil
I had a theory that the HPL monograde might have better cold start performance than anyone was giving it credit for. It has started just fine at 28F for me thus far without noticeable laboring on the starter or battery. We'll know more when winter returns.
I had a theory that the absence of VII could allow really low traction with a GTL base relative to the paper viscosity. While it's too soon to conclude that the monograde is indeed notably less traction somehow, the data is leaning that way. Certainly, the evidence to support the idea that an HPL monograde gives worse mpg because "it's too thick" seems to be vanishing before my very eyes. It turns out that there might be more to pumping losses than just HTHS or KV100.
I'm in a bit of disbelief myself. It got me questioning some of my own understanding. I suppose it's possible that at 20k miles the engine wasn't fully broken in and is only now getting there, but that seems quite unlikely to me overall given the prior oil usage (likely a blend) vs my oil usage.
I had a theory that no VII is really important when dilution is high and you want to mitigate the worst effects of dilution on piston ring deposits. Unfortunately, this one is almost impossible to assess. But directionally, I think it's safe to say that no VII is better than some VII for deposit prevention.
But let's step back and consider the three oil runs in context of MPG. With Valvoline Restore and Protect 5w-30 as the baseline, we'd assume of course than 15w-40 costs you some MPG. And indeed, we saw a loss of 0.2mpg which honestly is 1) very small and 2) explainable entirely by the difference in heating degree days of the two OCIs. The 15w-40 went through a full winter from Sept-Feb here. The Valvoline Restore and Protect never saw much in the way of real winter except for a couple starts early on with some late Feb snow.
That disparity in weather is why IMO the present run compared to Valvoline Restore and Protect 5w-30 is so relevant.
I think it's possible the real story here is not that monograde 40 is notably lower traction than 15w-40, but rather than all the HPL PCMOs are notably lower traction than the viscosity would suggest, and it might be the case that if I was running the 15w-40 again for this run (which duplicates the time of year the Valvoline Restore and Protect ran), then I'd also observe MPG trending higher than the Valvoline Restore and Protect run.
But as it is so far, the monograde is outrunning both the Valvoline Restore and Protect and the 15w-40 in mpg. I strongly suspect that the monograde in wintertime likely has a notable MPG penalty that has yet to show up. Time will tell, as I'm expecting to run this monograde a full year if the analysis supports it.
EDIT: The Heating Degree Days (HDD) of the Valvoline Restore and Protect period was 3912. The HDD value for the 15w-40 HPL run was 12% higher at 4378. So the HPL 15w-40 run had significantly more cold starts and colder average temperatures.
Which means it's possible the 15w-40 would deliver similar 29.3-29.5 OCI average MPG if allowed to benefit from warmer temps and summer fuel the way the initial Valvoline Restore and Protect run did.
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I hope you realize that we are going to expect you to re-run Valvoline Restore and Protect 5w30 at some point to validate / compare your previous run. Wake me up in 5 years when all the data has been charted? Please?!? 
Sorry, the second "a" in ABA testing is unlikely to occur as once I've established the HPL chemistry I'd like to keep it. If I go back to Valvoline Restore and Protect on 5k intervals, the data will come in naturally.I hope you realize that we are going to expect you to re-run Valvoline Restore and Protect 5w30 at some point to validate / compare your previous run. Wake me up in 5 years when all the data has been charted? Please?!?
For what it's worth, my tank MPG is now up to 32 (200 miles in) and the OCI mpg at just under 800 miles is now up to 29.9. The MPG enhancement of the SAE 40 appears to be a real thing. I can't explain it. It's the same fuel bought from the same stations, driven by the same driver on the route in the same usage.
Especially coming after a 6 month run of 15w-40 PCMO. What explains the MPG enhancement? How could removing 4% or so of VI do this? If it's not the oil, what else is it? I'm doing everything else the same as much as a person reasonably can do outside a chassis dyno. Same driver, same fuel (from the same pump at the same station).
I'm pleased but baffled.
Best theory I have now is that the 15w-40 would also show similar gains if given the benefits of nicer weather and the same duty cycle. But man, the notable smoothness increase of the monograde even over the 15w makes it hard to totally dismiss the idea that there's something special about this stuff.
Check your tire pressures.
did and done. Pressure are no higher than the Valvoline Restore and Protect run last year this time on the SAME rubber. And there's no way that lower pressure is lower rolling resistance.
Again, no obvious variable explains the MPG increase nor how it just switched on with the OCI to SAE 40.
Still a lot more miles to go, but the OCI average is converging at nearly a full MPG higher so far-- it's still climbing, albeit slowly.
I guess I’m no longer dipping toes. I’m in.
If you're getting better fuel mileage with all other factors that could impact fuel mileage held constant as well as possible and just changing the oil, it basically means there is an over-all less friction level between moving parts, even though theoretically the higher operating viscosity should cause more oil shearing friction/drag.
But if there is less friction on all the parts that are in the boundary and mixed lubrication regimes that could out weight the increase in oil shear drag. Also, a higher HTHS viscosity can reduce the friction (in addition to the the AF tribofilm additives) in the boundary and mixed regimes because it gives more MOFT and reduces mechanical contact of those moving parts - ie, separates the moving parts farther apart, thereby moving the operating points on the Stribeck Curve. What's the Moly level of the straight 40 grade HPL?
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Mid 600s, just like the 15w variant.
How's the HTHS viscosity compare between the 15W-40 and straight 40? How about the KV100 and specific gravity?
Comparing those specs could show that even if t they both have close to the same HTHS viscosity (measured specifically at 150C and 1 Million/sec shear rate), it could be that at shear rates below 1 Million/sec and at normal engine operating temps well below 150C in normal driving conditions the 15W-40 with VIIs may have more dynamic viscosity than the straight 40 grade with no VIIs. That might result in more overall shear drag with the 15W-40 than the straight 40 which could impact fuel mileage.
It basically comes down to If all other factors that could impact fuel mileage are being held constant and only the oil used was changed, and the straight 40 is showing better fuel mileage, then it has to come down to a difference in the overall engine friction level resulting from the oil.
Agreed. That’s mostly what makes the difference kind of baffling. The two 40 grades (15w and monograde) have nearly identical HTHS and KV100. So on paper they should essentially have identical pumping losses.
But my data is suggesting they do not, and that even the modest VII content of the 15w is enough to increase traction and reduce pumpability slightly. Enough to move an OCI mpg average from 29.0 to 30 (and climbing) so far.
But I’m thinking it’s more likely that the 15w and monograde are in fact quite similar, and the “mere” 28.8 OCI average of the 15w has everything to do with running all of winter and having all those cold starts in there.
The hypothesis that IMO makes the most sense overall is that BOTH the HPL 40 grades are lower traction than the Valvoline Restore and Protect 5w-30, which is why the monograde is besting the Valvoline Restore and Protect when testing during similar times of year. And lesser results of the 15w-40 are entirely due to seasonal effects.
I mean think about it this way: Would you expect to the difference between a 5w-30 run in predominantly warmer weather and a 15w-40 that went the entire winter to amount to a mere 0.2mpg? I sure wouldn’t. I’d expect it to be more like 2mpg or more in favor of the thinner oil.
Also, keep in mind that the monograde has a winter gauntlet yet to test it. There’s a good chance (a near certainty, actually) that the MPG of the monograde falls off a cliff once some truly cold weather comes in.
However, I’ve had several starts near freezing and already within a tank OCI haven’t noted major losses. So who knows, maybe the monograde really comes through the winter with flying colors like the 15w did.
Not sure exactly what your "pumping losses" comment is referring to ... the oil pump power required for each oil? If so, that's got to be minuscule between those two oils at operating temps. What's your term "increased traction" referring to? ... higher friction on moving parts, higher oil shear losses? More oil shearing loss would also contribute to higher engine friction due to oil shear vs the friction caused by parts actually rubbing together in boundary and mixed lubrication regimes. Just trying to understand these used terms which I haven't really seen used before.
What I'm talking about is the overall engine friction difference due to the actual dynamic viscosity at operating conditions which could be way more than the difference in the required oil pump hydraulic HP between the two oils at operating temperature.
If HPL ran both their 15W-40 and SAE 40 through a dynamic viscosity (cP) testing machine at a temperature of 200F (normal operating temps instead of 150C) and a shear rate well below 1M/sec, the 15W-40 would probably show a higher dynamic viscosity because it has VIIs but has the same basic HTHS as the SAE 40 that has no VIIs. The VIIs in the 15W-40 has to shear enough to make it have the same HTHS as the 40 with no VIIs. A higher dynamic viscosity at actual operating conditions on the road would mean more oil shear drag and theoretically cut fuel economy with all other factors held constant.
Quite possible since you haven't a lot of data to compare quite yet. A test like this would probably be best if both oils were ran for 6 months each, say one run from Oct thru Mar (the "winter run") and another run from Apr thru Sep (the "summer" run). Trying to gather a lot of data might take some time over testing along those lines.
Yeah, I'd expect the difference to be more than 0.2 mpg.
More time and data collection might shed more light.
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Do we have any low temp. cold start update on the SAE 40? The temp. in the Midwest just dropped to 35°F.
