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#4689168 - 03/08/18 09:15 PM Used Oil = less MPG... Any Proof?!?
Linctex Offline


Registered: 12/31/16
Posts: 6160
Loc: Waco, TX
I have about 9,300 miles on my OCI. (Frankenbrew, prob close to 5W-30-ish)

I filled today & calculated 18.1 MPG, about .2 mpg better than my "running average" of 17.9.

Has anyone actually done any REAL studies that says used oil = less MPG?
The motor oil companies all "say so".... but I don't think I've seen anything legit.
_________________________
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

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#4689179 - 03/08/18 09:24 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
maxdustington Online   content


Registered: 01/21/17
Posts: 681
Loc: Toronna
I read in Car Craft way back in the day that a fresh synth OC was worth 10 hp. Drag racers in restricted classes would change their oil after a few passes to maintain the effect.

I know that is not really proof, but this was during the early-mid 2000s when synthetic oil just started to become mainstream.
_________________________
03 Jetta AWP/09A 200k kms
Edge 0W40 + Mann 719/30

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#4689185 - 03/08/18 09:26 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
Dyusik Offline


Registered: 09/26/14
Posts: 1984
Loc: US-WA
The only reason I would believe that claim is when oxidation pushes the viscosity WAY up. That would take, what? 15? 20? 30k miles? Even at that, what are we talking about, 0.3%?
_________________________
95 Cherokee 190K DELO 10W30,XG8
07 IS250 97K FB ?w??,FULL
04 YZF-R1 19K DELO 15w40,XG7317
99 HD XL1200S 18K VR1 20w50,1515
14 RX450h 30k PP 0w20,NAPAG

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#4689211 - 03/08/18 10:00 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
PeterPolyol Offline


Registered: 03/06/16
Posts: 1345
Loc: toronto
Agree. The marketing guys are extrapolating oxidative thickening to a concept more palatable and arousing to the consumer, Horsepower.

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#4689214 - 03/08/18 10:02 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
JohnnyJohnson Online   content


Registered: 10/22/09
Posts: 2767
Loc: Wet side WA
I have run tests with my Duramax and Toyota Corolla with oils that claim to increase mileage. You could never prove it by me. A five to eight PSI change in tire pressure did thought in fact a couple MPG!


Edited by JohnnyJohnson (03/08/18 10:10 PM)
_________________________
2004 Toyota Corolla 121790
Out: QSUD 5W-30 Purolator One 5030
In: Valvoline ML 5w-30 TG4967 117530 2-8-18
2006 Duramax 74047
Out: T6 5W-40 M1-303
In: T6 5W-40 XG9100 73752 4-22-18

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#4689224 - 03/08/18 10:22 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
bbhero Offline


Registered: 03/20/15
Posts: 4630
Loc: Virginia
I have done 40 plus runs with checking my gas mileage new car old oil.

New oil= 29.4 to 29.8

Old oil= 28.4 to 28.8

And it was remarkably consistent. Every time past 4k miles running Pennzoil Ultra or Castrol gold bottle 5w30. Or around 2700 miles for other group 3 oils. Same road on Rte 5.

Doing something once, twice or three times is not meaningful to me. But having done it 40 plus times... It is and was shockingly consistent fall off. Pretty meaningful to me due to how many times I did it and how consistent it was as well.


Edited by bbhero (03/08/18 10:23 PM)
_________________________
Nissan Altima 3.5 Coupe Valvoline Advanced Full Synthetic 5w30 Federated Auto 4612ex
"Treat your family like your friends and treat your friends like your family."

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#4689232 - 03/08/18 10:32 PM Re: Used Oil = less MPG... Any Proof?!? [Re: JohnnyJohnson]
Linctex Offline


Registered: 12/31/16
Posts: 6160
Loc: Waco, TX
Originally Posted By: JohnnyJohnson
A five to eight PSI change in tire pressure did thought in fact a couple MPG!


Yes, the difference in heavy cars/light trucks is VERY pronounced.
The change seems smaller with lighter cars.
_________________________
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

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#4689233 - 03/08/18 10:34 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
Linctex Offline


Registered: 12/31/16
Posts: 6160
Loc: Waco, TX
Originally Posted By: bbhero

New oil= 29.4 to 29.8
Old oil= 28.4 to 28.8
And it was remarkably consistent. Every time past 4k miles


How odd.....
I would not have guessed that.
4,000 mile oil is usually still in tip-top shape. (ESPECIALLY Pennz U or Castrol GB)
_________________________
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

Top
#4689257 - 03/08/18 11:28 PM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
Ducked Offline


Registered: 10/25/12
Posts: 4386
Loc: Taiwan
Shear, thermal cracking and fuel dilution would be expected to go the other way.

This implies that, for a lot of oils over quite a high proportion of an OCI, any effects might cancel out, until you got to fairly terminal oxidative thickening.

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#4689291 - 03/09/18 01:24 AM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
bbhero Offline


Registered: 03/20/15
Posts: 4630
Loc: Virginia
Seriously Linctex.

Strange but a consistent pattern in both my Ford Fusion and my Nissan Altima 3.5. An interesting note is that Pennzoil Ultra and Castrol gold bottle both held up maximum gas mileage longer than any other oil I ran in either car.

All of the other oils started dropping between 2500-2800 miles.
_________________________
Nissan Altima 3.5 Coupe Valvoline Advanced Full Synthetic 5w30 Federated Auto 4612ex
"Treat your family like your friends and treat your friends like your family."

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#4689293 - 03/09/18 01:31 AM Re: Used Oil = less MPG... Any Proof?!? [Re: maxdustington]
Hemispheres Offline


Registered: 01/14/17
Posts: 381
Loc: Virginia
Originally Posted By: maxdustington
I read in Car Craft way back in the day that a fresh synth OC was worth 10 hp. Drag racers in restricted classes would change their oil after a few passes to maintain the effect.

I know that is not really proof, but this was during the early-mid 2000s when synthetic oil just started to become mainstream.


I can vouch. For the 1st 500 miles after changing my oil the engine is more responsive and pulls harder. The first couple fill ups after oil changes are pretty poor mpg wise as a result.
_________________________
2009 Buick LaCrosse (3800 Series III) - 137,000 miles.
PZ Plat HM/Mobil 1 HM
Bosch/Purolator/Mobil filters

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#4689384 - 03/09/18 08:13 AM Re: Used Oil = less MPG... Any Proof?!? [Re: bbhero]
Dyusik Offline


Registered: 09/26/14
Posts: 1984
Loc: US-WA
Originally Posted By: bbhero
I have done 40 plus runs with checking my gas mileage new car old oil.

New oil= 29.4 to 29.8

Old oil= 28.4 to 28.8

And it was remarkably consistent. Every time past 4k miles running Pennzoil Ultra or Castrol gold bottle 5w30. Or around 2700 miles for other group 3 oils. Same road on Rte 5.

Doing something once, twice or three times is not meaningful to me. But having done it 40 plus times... It is and was shockingly consistent fall off. Pretty meaningful to me due to how many times I did it and how consistent it was as well.

Change oil in winter/spring by chance?


Edited by Dyusik (03/09/18 08:15 AM)
_________________________
95 Cherokee 190K DELO 10W30,XG8
07 IS250 97K FB ?w??,FULL
04 YZF-R1 19K DELO 15w40,XG7317
99 HD XL1200S 18K VR1 20w50,1515
14 RX450h 30k PP 0w20,NAPAG

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#4689462 - 03/09/18 09:55 AM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
CT8 Offline


Registered: 10/09/14
Posts: 11009
Loc: Idaho
Clean oil is happy oil.
_________________________
"Don't let your preconceived notions get in the way of facts."
Geoff Metcalf

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#4689479 - 03/09/18 10:15 AM Re: Used Oil = less MPG... Any Proof?!? [Re: CT8]
69GTX Offline


Registered: 09/23/15
Posts: 3815
Loc: Connecticut
Ensure that the tests are all done at equal ambient temperatures. The density of air can vary up to 10-13% in summer vs winter in cold weather states.
_________________________
----------------

2001 Lincoln Cont 4.6L DOHC/ 39K mi / QS HM 5w30 / FUG XG2
1999 Camaro SS M6 /19K /Mobil 1 0w40 /Fram UG /GM MTL-ATF
1969 Ply GTX/RRs

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#4689480 - 03/09/18 10:16 AM Re: Used Oil = less MPG... Any Proof?!? [Re: Linctex]
supton Offline


Registered: 11/09/08
Posts: 11986
Loc: NH
Originally Posted By: Linctex
Originally Posted By: bbhero

New oil= 29.4 to 29.8
Old oil= 28.4 to 28.8
And it was remarkably consistent. Every time past 4k miles


How odd.....
I would not have guessed that.
4,000 mile oil is usually still in tip-top shape. (ESPECIALLY Pennz U or Castrol GB)


I believe Chris142 has indicated that, in order to pass CA smog, they often recommend an oil change. The new oil is better able to absorb blowby it seems, and thus engine out emissions is improved. If so, then I wonder: perhaps once the oil "loads up" with these lighter compounds, and no longer absorbs it, then any and all blowby is simply rerouted back into the engine. But this blowby now acts as "negative BTU's", or causes ignition timing to be pulled slightly, something, which causes a net loss of power (and thus an increase in fuel consumption). The oil could very well be still very good at what it does primarily (lubricate stuff).
_________________________
2011 Toyota Camry, base, 2.5L/6MT, 162k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 143k, ours
1999 Toyota Camry LE, 2.2L/4AT, 183k, his

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