True economics of extended oil drains

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ASTM D7589

https://www.astm.org/Standards/D7589.htm

OK, this one costs money, maybe there is a free download to be had in the ether.

Basically fuel economy savings from resource saving engine oils vs a base-line oil disintegrate with age in use.
For example; xW20 resource conserving provides a 2.6% savings when fresh, but only 1.2% after 100 hours in the sequence test.
Other grades drop 1% over the same time.
At some point, there would be no fuel savings, and extending the drain further to save a few quarts of oil, will cost you gallons of fuel.
 
I base the interval on how everything is doing inside the engine and not any financial considerations. I'd have a stroke if I had to rebuild my 4Runner's V8 engine for trying to save a few dollars on engine oil.
 
I've always regarded these tests as providing highly misleading information.

Sequence VID fuel economy is measured relative to a 20W30 oil; an oil grade that the US probably stopped using as a PCMO when multigrades were widely adopted in the 1950s! It would make far more sense to measure FE against something like a 10W30 which was the de facto oil in the US for many years but of course then, the indicated fuel economy gain would be far smaller and Joe Public might justifiably ask 'Resource Conversing? Really?Are you pulling my plonker??'

Given that the Sequence VID was first used in GF-5, around 2008/2009-ish, it would have been far more honest to use a 5W30 oil as the base line reference oil because it was by then already the dominant oil grade.

There's another dimension to this. I can't speak for the VID which arrived as I was departing, but it's predecessor, the Sequence VIB, was the most God awful of tests and bordered on being a random number generator! New VIB engines would always start off a bit 'tight'. Getting a passing result on a new engine was always nigh on impossible. Then as the engine started to loosen up, you might just be within a shout of getting a pass but it still could bounce either way. As I recall, there would come a time when the engine was so loose that it fell out of calibration and the entire sorry state of affairs would have to start again.

Finally, I have always disliked how overambitiously set VIB/VID targets have driven US PCMOs to ever lower CCSs to pass these fuel economy tests. The result is a preponderance of US oils with stupidly high Noacks, laden with excess VII polymer that just shouldn't be there.

Rant over...
 
when you say gallons of fuel it is literally like 2 to 3 gallons.

If you get 25mpg, 200gallons is 5000 extra miles extension on your oci.

So say you extended by 5000miles on less efficient oil, you lost 1% so you are out 2gallons of fuel...
 
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Nevertheless, tests show an increase in fuel consumption over time. If the cause was increased viscosity from evaporation loses, that would be understandable. If fuel use per HP/HR or the metric equivalent, increased as the engine oil viscosity decreased from shear, dilution or whatever, then other factors would be at play. Depletion of friction reducing and/or AW additives being a possibility.

Edit; Engine oil is recovered when recycled, fuel is lost.
 
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In the lifetime of the ILSAC test protocols, I would hazard a guess that way more gasoline has been wasted in trying to demonstrate the fuel economy benefits of engine oil than was ever saved in real life engines. Which is crazy when you think about it!

Also, whilst I can't recall doing any detailed analysis of what goes on during fuel economy tests (outside of the US, FE wasn't that big a requirement and 'my' American equivalents were always rather keen to keep me well away from what they were doing for fear I might be beastly to them!) I wouldn't at all have been surprised to find that declining FE in Phase 2 of the Sequence VIB/VID tests was linked to high evaporative loss causing viscosity to increase, which in turn was linked to the very high Noacks you needed to pass Phase 1 of the test. Quite ridiculous when you say it out loud but I suspect it's not a million miles away from the truth.
 
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I've been doing 10K OCIs for 39 years and have never noticed any decrease in MPG toward the end of an OC. I have taken several long trips with 7-8K on an OC and the MPG stayed within the norms for my engines.
 
The benefits of extended drain for me is quantified in hours not spent in the garage that otherwise could be spent with my family. Or alternately, getting me through the summer so I can change the oil when it's nice out and not 100F. If I burn a little extra gas so be it.

[edit] ok, so another factor is, it feeds my motor oil "hobby" to determine what drain interval I can safely use. Haha.
 
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Lol, I think most of us spend more time on BITOG & dreaming of changing oil, than actually doing it.

Like moving to a thinner oil, a 1 or 2 percent change in fuel economy would not be noticed, except in a fleet operations.
 
Originally Posted By: SonofJoe
In the lifetime of the ILSAC test protocols, I would hazard a guess that way more gasoline has been wasted in trying to demonstrate the fuel economy benefits of engine oil than was ever saved in real life engines. Which is crazy when you think about it!


True!
grin.gif


Originally Posted By: tig1
I've been doing 10K OCIs for 39 years and have never noticed any decrease in MPG toward the end of an OC. I have taken several long trips with 7-8K on an OC and the MPG stayed within the norms for my engines.


Same here. I watch it closely, and I'm definitely not getting "worse" gas mileage at the end of my OCI.
 
ASTM D7589 allows a max 1% fuel economy loss after 100 hours for a pass. Assume 2% @ 200 hours, the typical oil drain interval, for a 1% average loss from new.
If the 2nd 100 hour interval obtained 1% less fuel economy than the 1st 100 hours, depending on application, changing the oil early may be a net cost savings.
 
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Originally Posted By: userfriendly
ASTM D7589 allows a max 1% fuel economy loss after 100 hours for a pass. Assume 2% @ 200 hours, the typical oil drain interval, for a 1% average loss from new.
If the 2nd 100 hour interval obtained 1% less fuel economy than the 1st 100 hours, depending on application, changing the oil early may be a net cost savings.


Just bear in mind that the Sequence VID Phase 2 84 hour oil aging is carried out with a fixed bulk oil temperature of 120°C. This isn't quite as extreme as something like the Sequence IIIG test but it's probably quite a lot more extreme than most run-of-the-mill driving conditions. Given that 84 hours of cooking & mashing up the oil at 120°C is likely to promote some viscocity increase, either from evaporating off the light front-end of the oil or by simple oil oxidation, then you could reasonably expect the FE quality of the oil to be worse at the end of the test. However, that's probably more an artifact of the test itself, rather than something that reflects what you see in real life driving conditions.
 
Would your 10W20 proposal fix some of those issues?

Edit; I noticed that Havoline 10w30 in 2 flavors and the Delo FA-4 offering just barely make the SAE 30 grade.
It's good to see someone is finally listening and watching bitog posts.
 
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Originally Posted By: userfriendly
ASTM D7589

https://www.astm.org/Standards/D7589.htm

OK, this one costs money, maybe there is a free download to be had in the ether.

Basically fuel economy savings from resource saving engine oils vs a base-line oil disintegrate with age in use.
For example; xW20 resource conserving provides a 2.6% savings when fresh, but only 1.2% after 100 hours in the sequence test.
Other grades drop 1% over the same time.
At some point, there would be no fuel savings, and extending the drain further to save a few quarts of oil, will cost you gallons of fuel.


Based on controlled testing, I'm sure the data is true. It would have to be. Oil is going to break down and change. In real world situations there's too many variables to quantify, but over 10's of 1000s of engines it's probably still true.
 
Oil is cheap these days, and I don't consider my vehicles a utility like most; they are part of the family. As such, they get fresh oil every 5K. Both are spotless under the valve cover, and it's worth the peace of mind running them hard when I know the oil is fresh.
 
Originally Posted By: userfriendly
Would your 10W20 proposal fix some of those issues?

Edit; I noticed that Havoline 10w30 in 2 flavors and the Delo FA-4 offering just barely make the SAE 30 grade.
It's good to see someone is finally listening and watching bitog posts.



Of darling, 10W20 is SOOOO last year! We (well maybe just me) are now pushing 10W16 as the right oil for all sensible people everywhere (sorry Canada but no sensible person lives in a country as cold as yours!).

10W16 would probably suffer the same problems as other oils in being put through the VIB/VID but sensibly done, possibly as a semi-synthetic, you could get the Noack to a place where Phase 2 fuel economy wasn't that different to Phase 1's.

Of course, the sensible thing to do would be to just not fanny around doing these tests in the first place! The need for 'proof' is trumping common sense. I was once informed, by someone that was in a position to know, that one oil major ran 200 Sequence VIBs just to get one passing test, so that they could add a fuel economy claim to their oil (it's One you will definitely have heard of). In industry parlance we would call this a 'one in plenty pass'! How can anyone think this is remotely sensible or scientifically meaningful?
 
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Apparently there won't be a GF-6 5W16, just 0W16. Would it need to be tested and marketed as "resource conserving"?
I doubt there would be a measurable fuel economy difference between SAE 16 grades, but the higher VI offerings will likely have higher NOACK.
 
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