FYI: this oil starts effortlessly in my car down to 28F and the recent cold snap hasn’t attained anything surpassing that for cold. It started perfectly at freezing temps again a few days ago.
HPL SAE 40 PCMO
- Thread starter Hohn
- Start date
Just pulled the 1k sample. the mpg bonus seems real, as it’s still slowly ticking higher. It’s on pace to be almost exactly 1 mpg better. As a reminder for those who didn’t read the whole thread, the 4507 mile data was Valvoline Restore and Protect 5w-30, run from Feb-Aug last year. The 4753 mile data is HPL 15w-40 run from then until I put the monograde in March 13, 2026, so it had the handicap of a full winter. We are not yet on summer fuel here.
Last edited:
And the oil is the only variable in your everyday driving? Even at the same gas station the energy content of gasoline can vary about 4% irrespective of seasonal changes.
Here’s a good point of reference from someone who knows a lot more than I do:
The graph below represents several years of my actual MPG that I calculated on each fill-up. Same driver, same car, same oil brand and grade, and mostly same gas station. The spikes up and down are from long freeway trips or traffic jams, but most of the data falls between the red lines, which is +- 14% from the average, a 28% range! Trying to attribute a couple of percent move (i.e. 0.5 mpg) to changing one variable is not possible from such point scatter.
And here are a few of the variables that can affect fuel economy:
And here are a few of the variables that can affect fuel economy:
- Tire pressure
- Tire...
Last edited:
And the oil is the only variable in your everyday driving? Even at the same gas station the energy content of gasoline can vary about 4% irrespective of seasonal changes.
Here’s a good point of reference from someone who knows a lot more than I do:
The graph below represents several years of my actual MPG that I calculated on each fill-up. Same driver, same car, same oil brand and grade, and mostly same gas station. The spikes up and down are from long freeway trips or traffic jams, but most of the data falls between the red lines, which is +- 14% from the average, a 28% range! Trying to attribute a couple of percent move (i.e. 0.5 mpg) to changing one variable is not possible from such point scatter.
And here are a few of the variables that can affect fuel economy:
- Tire pressure
- Tire...
I think it's well established the OP is looking for validation to continue running this choice of oil. It seems to be working for his use case, fair enough. But yeah, 1 MPG difference is insignificant. As you stated in that older thread you linked to, there is no such thing as "real world" with regards to repeatable testing.
He is not looking for validations. He is experimenting with SAE 40 high end synthetic oil in a car specified for 0W-20.
He is looking for optimum lubrication of his water pump lobe which is driven by the camshaft. It looks like the oil film of 0W-20 is not thick enough, that's why he is trying higher viscosity oils.
The thing here is that this is also a promo of this oil as one of a kind full synthetic SAE 40 which no other company makes. Other companies have 0W-40, 5W-40, 10W-40, 15W-40 full synth, but not SAE 40.
Sort of yes. The 4% value I quoted came from an article I linked here once from an entity that was attempting to measure real-world fuel economy. They concluded that even with the same driver on a small closed track with similar weather and temperature it was impossible to obtain consistent results without using standardized BTU test fuel.
Once in the uncontrolled real world with the myriad of significant variables, a determination is literally impossible. The effect of the oil is deep in the noise and buried below other and more significant effects. @Tom NJ does a good job of listing those variables and illustrating the problem.
You're out of your element donnie. Just stop BROTELLA.
Certainly the moly in HPL is a friction modifier. But I’m surprised it can offset the significantly higher HTHS of the HPL oils in terms of pumping loss.
A small loss of mpg is a reasonable expectation when jumping so high in hths and rite grades above OEM viscosity recommendation.
But a net gain with the 40 grades above a 5w-30 seems noteworthy.
On a long enough horizon, all that variation averages out. That’s why my two prior OCI showed remarkable stabilization.And the oil is the only variable in your everyday driving? Even at the same gas station the energy content of gasoline can vary about 4% irrespective of seasonal changes.
Here’s a good point of reference from someone who knows a lot more than I do:
The graph below represents several years of my actual MPG that I calculated on each fill-up. Same driver, same car, same oil brand and grade, and mostly same gas station. The spikes up and down are from long freeway trips or traffic jams, but most of the data falls between the red lines, which is +- 14% from the average, a 28% range! Trying to attribute a couple of percent move (i.e. 0.5 mpg) to changing one variable is not possible from such point scatter.
And here are a few of the variables that can affect fuel economy:
- Tire pressure
- Tire...
Regression to the mean is a thing. Look it up.
The entitlement here is mpg loss with monograde. The question is how much loss the monograde would incur.
But instead the data is showing steady increase on the monograde.
Nobody is more surprised than I am. But I assure you it’s real—as real as any testing outside a chassis dyno could replicate.
Just curious, do you think a HPL 30 monograde would behave in the same manner or are you thinking it’s simply the higher HTHS of the mono 40?
I’m curious and I test things as best I can without the benefit of the expensive test cells we use at work.
The monograde experiment really only came from curiosity after having incredibly good performance with the 15w-40 PCEO.
I’m not looking validation in the sense that I have utmost confidence in both Valvoline Restore and Protect and HPL if used within limits. Either will keep my engine alive longer than the rest of the car.
This experiment is purely to explore what happens when you take the last bit of VII out of a 40 grades HPL PCEO formula.
And also perhaps to dispel some myths about this oil being “too thick” for street driving year round in the Midwest.
Everything I’ve read says higher HTHS is worse for mpg. That why lower hths is the focus of so much research.
I personally suspect the monograde 30 might be even better mpg.
But the data so far confounds my understanding of conventional wisdom.
No, that does not apply here. That's the issue, you're trying to measure a variable well in the noise and no matter how long you run the test you'll never raise it above the noise. It's impossible.
Has there been any studies comparing the dynamic viscosity of mono-grade oil to one with lots of VII, both having the same HTHS viscosity, but at lower temperatures and shear rated than the defined HTHS of 1M/sec and 150C?
At lower shear rates than 1M/sec and lower temp than 150C it could be the xW-40 with VIIs has higher dynamic viscosity than the mono-grade 40 at the same lower shear rate and temperature. In order for both of then to have the same HTHS, the oil with the VIIs would need to basically shear the VIIs down to nothing, which means at conditions less than the HTHS operating point the dynamic viscosity of the oil with VIIs can be higher than the mono-grade with no VIIs. If you're not driving around a pretty high RPM all the time, then the oil between most of the moving parts is going to below the 1M/sec and 150C operating conditions.
A lab like what HPL has could probably measure the dynamic viscosity at points below the HTHS conditions (less shear at less temperature) and could see this phenomena.
Could be.
But these days I'm thinking my data really comes down to HPL vs non-HPL. That 15w-40 holding within 0.2mpg of the Valvoline Restore and Protect 5w30 while having no summer fuel and all the cold starts and cold enrichment? THAT is the real story hiding in plain sight. Winter is notorious for killing fuel economy-- you're running defrost (and a/c) frequently, sitting in drive-throughs, letting cars warm up, etc. Freezing cold intake air keeps fuel from vaporizing readily and dilution skyrockets in cold TGDIs.
SO what I'm seeing in the monograde is almost certainly what I would have seen with the 15w-40 under the same seasonal effects.
Therefore I suspect the real story here is not monograde vs 15w; how could eliminating a tiny bit of VII move the needle so demonstrably? It really can't. Not when HTHS and KV100 are essentially identical.
No. Rather, the real story here is HPL's GTL bases and their low traction combine with the superb HPL friction modifier package (600ppm moly) to deliver 40 grade oils with less pumping loss than a group III 5w-30.
That, I think is the real story this data supports. Both HPL 40 grades are slicker than a Valvoline Restore and Protect 30 grade. They have less sliding friction and almost certainly lower traction as well.
It's what happens with the dynamic viscosity between zero shear and what happens as the temperature plus the shear rate is increased. So an oil with VIIs can have higher dynamic viscosity at some temperature and shear rate below the HTHS test point than an oil with no VIIs. So theoretically, if all factors could be held constant the mono-grade 40 should result in less dynamic viscosity in an engine cruising around town with parts shearing the oil under conditions well below the 150C and 1M/sec shear rate that the HTHS viscosity is mearued at.
What's the difference between traction and friction in your comments? Never heard the term "traction" used wrt to oil function.
Traction is a slightly more specific subset of friction in a lube context. It has to do with how the oil transmits “grip” between two surfaces under rolling or sliding contact when there’s a high unit loading.
https://www.stle.org/images/pdf/STL...raction Curves and Rheological Properties.pdf
https://www.stle.org/images/pdf/STL...raction Curves and Rheological Properties.pdf
- Joined
- Dec 16, 2022
- Messages
- 1,379
Isn't that "stiction"? I remember that word because an engineer inspected a failed hemi cam and used that word, basically saying the oil did not have enough stiction so there was excessive play/slip between cam lobe and lifter.
Looks to be a term used to describe a system level of friction based on all factors involved, like oil formulation, dynamic viscosity, shear rate of the oil, load on the moving parts (which relates to the level of contact and resulting MOFT) and what realm of lubrication. In pure hydrodynamic lubrication, the moving surfaces contact factor is gone. In boundary and mixed lubrication, the anti-friction additives can also play a role when the surfaces are physically rubbing. Basically it's a term for "What's the overall friction level between two moving parts affected by all factors involved".
Last edited:
