AAA: Not All Gasoline Created Equal

[plus 3 golfer]

There have been discussions in the past on quality of gas, specifically Top-Tier gas vs non Top-Tier gas. Here's AAA recent take:

 

“AAA was surprised to learn the extent to which detergent additives impact gasoline quality,” revealed John Nielsen, AAA’s managing director of Automotive Engineering and Repair. “As advertised, tested TOP TIER gasolines kept engines remarkably cleaner than other fuels we tested.” Link to Article

 

“When it comes to selecting a gasoline, automakers got it right – TOP TIER gasoline performs best,” continued Nielsen. “By selecting a quality gasoline, drivers can minimize engine deposits, increase vehicle performance and improve fuel economy.”

 

I've been using only Top-Tier gas for the last 10+ years and it's generally within few cents of the cheaper non-branded gas.

[scottwood2]

I wonder what Costco uses?  They always talk about the benefits of their detergent gasoline.  Not sure if they just buy based on cost or do they have deals with a brand of gas? 

 

I looked for result in the report but I did not find the brands they tested. 

[markd]

It is forty cents a gallon more expensive here in Indiana.

[SnowStorm]

I wonder what Costco uses?  They always talk about the benefits of their detergent gasoline.  Not sure if they just buy based on cost or do they have deals with a brand of gas? 

 

I looked for result in the report but I did not find the brands they tested. 

It is listed here - so you should be good.

[raadsel]

I wonder what Costco uses?  They always talk about the benefits of their detergent gasoline.  Not sure if they just buy based on cost or do they have deals with a brand of gas? 

 

I looked for result in the report but I did not find the brands they tested. 

 

 

It is listed here - so you should be good.

 

Costco also lists their gasoline as Top Tier on their website.

[plus 3 golfer]

It is forty cents a gallon more expensive here in Indiana.

We are talking about Top-Tier gas not premium gas vs regular gas.  Look on Gasbuddy.com, select the Map display and then select to display TOP-TIER stations only.  

 

Currently, near me (within 2 miles) Top-Tier Mobil is $1.99 (regular) and $2.45 (premium) and non branded is $1.97 (regular) and $2.39 (premium). The leak and shutdown of the Colonial Pipeline has caused about a $0.15 per gallon increase in Eastern TN gas prices since mid last week.  Supposedly tomorrow, fuel will start flowing again in the pipeline.  We'll see how long it takes stations to lower prices $0.15. :)

Edited September 20, 2016 by Plus 3 Golfer

[ptjones]

I have been using BJ's for along time with no noticeable loss in mpg's.  I have used Techtron, Texaco octane booster and NOS Octane Booster( they all are suppose to clean injectors), I have 136k mi. and getting great MPG's.  I'm thinking about using NOS Octane Booster to start my next trip. :)  I find it interesting that they don't mention the difference in Octane for the same grade around the country. :headscratch:

 

Paul

[plus 3 golfer]

I have been using BJ's for along time with no noticeable loss in mpg's.  I have used Techtron, Texaco octane booster and NOS Octane Booster( they all are suppose to clean injectors), I have 136k mi. and getting great MPG's.  I'm thinking about using NOS Octane Booster to start my next trip. :)  I find it interesting that they don't mention the difference in Octane for the same grade around the country. :headscratch:

 

Paul

See this published today.  AAA finds no benefit in using premium vs regular gas in most cars.  So my presumption is that AAA wouldn't find a difference between 85, 86, or 87 octane fuel either.

 

I would think that using Techron every so often would offset the advantage of Top-Tier gas has over non-Top-Tier gas relative to the amount of detergent additives in the gas. Also, BJ's may have more additives than required and simply choose not to become a Top-Tier marketing.

 

I think I said this before but my 2000 Passat would "carbon up" (symptom lots of misfires, hesitation on hard acceleration) every 12 -15 k miles (first time VW dealer used a BG system to clean injectors, piston top and cylinder).  I subsequently began to put Techron in every 10k miles or so and had no more issues.  Eventually (maybe 2005 or so), VW came out with a TB indicating that owners should use Top-Tier gas in their vehicles because of the additional detergent additives.  That's when I started using Top-Tier gas in all my vehicles.  Even though I do use Top-Tier gas, I still dump a bottle of Techron in every 20 k miles or so.

 

Quote from link above:  "Researchers tested the vehicles on a treadmill for cars, called a dynamometer, to evaluate the effects of using premium in cars that did not require it. The lab testing found no significant increase in horsepower, fuel economy and tailpipe emissions.

 

“Premium gasoline is specifically formulated to be compatible with specific types of engine designs, and most vehicles cannot take advantage of the higher octane rating,” said Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center."

 

 

[ptjones]

See this published today.  AAA finds no benefit in using premium vs regular gas in most cars.  So my presumption is that AAA wouldn't find a difference between 85, 86, or 87 octane fuel either.

 

I would think that using Techron every so often would offset the advantage of Top-Tier gas has over non-Top-Tier gas relative to the amount of detergent additives in the gas. Also, BJ's may have more additives than required and simply choose not to become a Top-Tier marketing.

 

I think I said this before but my 2000 Passat would "carbon up" (symptom lots of misfires, hesitation on hard acceleration) every 12 -15 k miles (first time VW dealer used a BG system to clean injectors, piston top and cylinder).  I subsequently began to put Techron in every 10k miles or so and had no more issues.  Eventually (maybe 2005 or so), VW came out with a TB indicating that owners should use Top-Tier gas in their vehicles because of the additional detergent additives.  That's when I started using Top-Tier gas in all my vehicles.  Even though I do use Top-Tier gas, I still dump a bottle of Techron in every 20 k miles or so.

 

Quote from link above:  "Researchers tested the vehicles on a treadmill for cars, called a dynamometer, to evaluate the effects of using premium in cars that did not require it. The lab testing found no significant increase in horsepower, fuel economy and tailpipe emissions.

 

“Premium gasoline is specifically formulated to be compatible with specific types of engine designs, and most vehicles cannot take advantage of the higher octane rating,” said Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center."

We have been this before and for me experience "Trumps" researchers generalities every time.  This has been the case for 3 FORD Aerostars, FORD Focus and CMAX.  All of My Mustangs used Premium. :)  Haven't tried it with my New F150 because it has 36 gallon tank which means $10-$15 extra per fillup. :drop:

 

Paul

[plus 3 golfer]

We have been this before and for me experience "Trumps" researchers generalities every time.  This has been the case for 3 FORD Aerostars, FORD Focus and CMAX.  All of My Mustangs used Premium. :)  Haven't tried it with my New F150 because it has 36 gallon tank which means $10-$15 extra per fillup. :drop:

 

Paul

I've never seen a study indicating that premium gas provides any significant FE benefit over regular for engines that are set up to burn regular fuel.  I find it hard to believe that Ford has any magical equipment / software that can extract significant FE benefits from premium gas that others can't or wouldn't implement.  Certainly nothing that makes using premium economical.  I believe I stated in prior threads that I could only believe that FE would likely increase using premium for 2 reasons - spark retard during faster acceleration with regular over premium and premium might have more BTUs than regular.  Here's one finding in the study: "Differences in vehicle performance / control of ignition timing were apparent only when the test vehicles were operated in an aggressive manner.  

 

In the study, certified testing of the gas showed the regular fuel had 0.6% more BTU content than the premium fuel. There is certainly a possibility that marketers may sell premium fuel with a lower blend of ethanol than in their regular gas and hence the premium gas may give significantly better FE because its BTU content is significantly greater than the regular. But when comparing regular and premium in real world driving, we don't know the ethanol blend that we are purchasing.  All we know is how much more we are paying for premium over regular. Are we paying for more BTUs also?  So, if the gain in FE using premium doesn't pay for the extra cost of the premium fuel, consumers are wasting dollars on premium fuel.

 

Here's the study and for those that don't want to read it, the FE graph from the study.  The FE increases using premium are marginal (tenths of a MPG or 1% on a few of the test cycles).  Even if one could "hypermile" appropriately and increase it 5X to say 5%, economically using premium makes no sense which I believe is the main point AAA is trying to make - "U.S. drivers waste $2.1 billion annually by putting Premium gasoline into vehicles designed to run on Regular."

 

 

 

Premium-Fuel-REPORT-FINAL.pdf

Edited September 21, 2016 by Plus 3 Golfer

[fbov]

The first thing to look at is the objective of the test. 

 

Not the stated objective, that actual objective, as determined by the test conditions. How you set up a test determines the answer you get. AAA used three conventional drive trains (engine, multi-speed transmission). They proved that premium has no benefit for conventional drive trains across a reasonable displacement range, unless required by design.. 

 

An interesting test would be to use a vehicle with better fuel economy at low speed than high speed. One whose energy use is actually linked to the amount of energy needed to get from one place to another in a given period of time. Instead, they chose vehicles that waste the vast majority of the fuel's energy content. 

 

No one should be surprised at the results. The test is designed to insure those results. That's a rigged test in my book. Puts AAA right up there with Mythbusters. Sad.

 

HAve fun,

Frank, who has proven these results to be incorrect. Better fuel gives better mileage, if you're not wasting it. 

[ptjones]

Ken,  if your point is that it isn't cost effective to use Premium now with gas prices around $2.30/ gal I would agree with you. When gas prices were $4/gal, then it was close. 

With the improved FE of Premium the net cost is around $2/ tank so I rationalize the better FE is worth $2. :)

The reason Premium gets better FE in you FORD CMAX is that the ICE uses a knock sensor to adjust the timing, the more advanced your timing is, the more time the gas mixture has to burn which improves efficiency and FE.  In almost all cases on the AAA test Premium got better FE. :yahoo:

For those CMAXer's wanting to try an experiment, try filing up with Premium and then add NOX Octane Booster from Walmart($10, it will clean your injectors and add 2 octane points). Remember to use the funnel in the trunk to put the NOX Octane Booster in the tank.   :)
Would like to hear what other members get for an improvement. :shift:

 

Paul

[plus 3 golfer]

Paul, I always weigh the opportunity costs for decisions or actions like in this discussion.  :)  Significant to me means that any actions taken must be more than break even.  Close is not good enough.  So, even if premium resulted in a 10 % increase in FE, I wouldn't use premium unless regular gas was near $5.00 a gallon assuming a $0.40 additional cost for premium.

 

The % FE improvements needed to break even on premium gas or NOs is simple math and only depends on the difference in price of premium vs regular gas, the additional cost of NOs per gallon, and the expected % FE increase. Ones actual FE doesn't matter.  

 

For example, assume premium gas cost $0.40 per gallon more than regular.  Then for a 10% increase in FE using premium, regular gas prices must be greater than ($0.40 / 10%) = $4.00 per gallon for it to be economic to switch to premium.   If FE increases only 5% when using premium then the break even regular gas price is $8.00 per gallon.  I don't ever recall seeing $4 per gallon gas. :)  Using NOs has a higher break even. Working backwards, assume that regular gas sells for $4.00 per gallon. If I could pay $4.40 for premium, I would need a 10% FE increase to break even filling up with premium vs regular.  Same logic applies for NOs.

 

Here's my anecdotal test of premium gas.  On our last trip to Phoenix in July 2016, I filled up with premium fuel on three successive fill-ups on I-40 between Memphis and Amarillo (eco-cruise set between 73 and 78 mph based on speed liimit) and closely watched FE for the tanks and spark timing and compared actual FE with the tanks with past performance.  I had made that same trip across I 40 5 times in the preceding 13 months - June 2015, July 2015, August 2015 and 2 times in September 2015.   I can say with certainty that there was not a 10% FE improvement (would need 3.8 mpg increase) using premium on any of the tanks, not even a 5% FE improvement (around 2 mpg), but maybe a 1 - 2 % improvement (around 0.5 mpg).  Second, spark advance may have been slightly higher on the tanks as it appeared that the occurrence of higher spark advance data appeared more frequently although I saw the max. advance (40* IIRC reading somewhere) on many occasions with regular and premium.

 

I'll do this, I'll buy a can of NOs and run tests before and after trying to keep conditions similar at high speed on the interstate and at lower speeds 35- 55 mph or so.  I'll record the spark advance (and other data available on that module), snap pics of the trip displays and so forth.  I may not get to this for a month or so.  

 

I would drive about 5 miles to reach operating temperature.  Then, fill the tank up with regular at my regular Mobil station.  Drive about 50 mile round trip  back to the Mobil station.  Dump in the NOs and drive about 20 miles or so to ensure the NOs is mixed and being burned.  Repeat the 50 mile round trip.   It will likely take me over 2 hours to complete.

 

The 2nd other option is to start the test with maybe 1/2 tank of regular and complete the 50 mile first leg.  Dump in the NOs and fill with premium.  Continue the test.  This would get me close to a 93 octane on the last 50 mile round trip.

 

I think I should do the 2nd option which would yield a higher octane fuel in the 2nd loop and better chance of seeing a FE increase.

 

 

[SnowStorm]

A few related thoughts:

1. Would love to see a similar test on 87 E10 versus 87 E0 (no ethanol).  There is no argument (AFAIK) about E0 giving better mileage but it would be nice to see some real test numbers.
2. For the 2nd option you may want to carry some "ballast" on the half tank voyage equal to about 6 gallons of fuel - then toss it overboard for the full tank voyage!  Can't have a weight difference messing things up!
3. And watch beginning and ending SOC for sure.  A big difference there could easily overwhelm the octane difference IMO.
4. Once you're seriously into the "Hybrid Hobby" (getting highest possible MPG), cost per mile can take a back seat to MPG - just depends on your goal.

Personally, I wouldn't pay the extra 22% for Premium but that's just me.  I do pay a premium for E0 (over the MPG savings) because I don't want to run 1000s of miles of ethanol through my engine.

[plus 3 golfer]

Yes, I thought about the ballast. I always adjust mileage for significant differences in SOC.  Over 50 miles several % points won't matter.  A 10% difference (SOC 45% to 55%) is around 0.14 kWh.  At 4 miles / kWh (very optimistic), that's only 0.56 miles or about a 1.1 % effect.

 

I agree if FE is a hobby, then economics is not material.  But, for the general consumer as AAA says:   "Today, many motorists believe that Premium grade gasoline will give engines designed to run on Regular a variety of benefits, including more power, lower tailpipe emissions, and better fuel economy."   That's like me trying to convince a beginning golfer to believe that spending $1500 for a new set a golf clubs will improve their game when a $200 set of used clubs will be just as good. There's really not much benefit between the two.  Don't expect to lower your handicap by 22% with new clubs. :)  Yet, the hobbyist by neglecting to point out the opportunity cost of buying new clubs vs used or premium gas vs regular does IMO a disservice to the unwary consumer.

 

There's a station about 1 mile from me that sells only pure gas.  E0 regular is currently $0.44 a gallon more than E10 regular and E0 premium is $0.74 a gallon more than E10 regular.  I'll let someone else run that test as we know just from a BTU standpoint that E10 will decrease FE around 3% (2 - 7% decrease in FE has been reported).

 

"Pure gas gives better mileage than E10, and much better than E85, simply because gasoline has higher free energy than ethanol. The free energy of gasoline is 34.2 MJ per liter. The free energy of ethanol is 24.0 MJ per liter. That means E10 (10% ethanol) has a free energy of 33.2 MJ per liter, and E85 (85% ethanol) has a free energy of 25.6 MJ per liter. As a result, your mileage is reduced by 3% with E10 over pure gas, and 25% with E85 over pure gas, all else being equal. Mileage will be reduced even more if your engine doesn't run as well on E10, which is often the case with older vehicles."

[ptjones]

Plus 3 Golfer

"Pure gas gives better mileage than E10, and much better than E85, simply because gasoline has higher free energy than ethanol. The free energy of gasoline is 34.2 MJ per liter. The free energy of ethanol is 24.0 MJ per liter. That means E10 (10% ethanol) has a free energy of 33.2 MJ per liter, and E85 (85% ethanol) has a free energy of 25.6 MJ per liter. As a result, your mileage is reduced by 3% with E10 over pure gas, and 25% with E85 over pure gas, all else being equal. Mileage will be reduced even more if your engine doesn't run as well on E10, which is often the case with older vehicles."

 

 This doesn't take into account the differences in Octane which adds another level of complexity. :drop:

Looks like tomorrow we will start a trip along the GA, SC and NC coast looking at Lighthouses for a few days. Plan on using State Routes for improved FE to see if we can make it to 1K miles on a tank. :) 

 

Paul

 

 

[tr7driver]

So, is the efficiency differences between gasoline types measured by the AAA test in conventional ICE engines the same in our Atkinson cycle engines?

[plus 3 golfer]

So, is the efficiency differences between gasoline types measured by the AAA test in conventional ICE engines the same in our Atkinson cycle engines?

The C-Max engine is an Otto Cycle engine but with delayed intake valve closing (simulated Atkinson cycle).  So, the effective compression ratio is lower than the actual - likely around 10:1 or less compared to maybe 13:1 (don't hold me to these numbers :)).  Thus, IMO the efficiency of our engine is greater because pumping losses are reduced during compression but allowing full expansion during the power stroke.  This reduced loss would not be affected by gasoline types.

 

EDIT:  Below is the actual variable cam shaft operations for the C-Max.  The AAA test engines may have similar controls to help reduce emissions and improve FE.  I don't know.  But I doubt this operation would be affected by Octane in the gas.  Octane affects detonation and vehicles have knock sensors. The PCM would retard timing when the threshold level of detonation is reached.  All modern vehicles do this. The question is how far do the PCMs allow timing to be advanced?  Again, my guess is modern engines would all have similar control logic.

 

 

"Variable Cam Timing (VCT) enables rotation of the camshaft(s) relative to the crankshaft (phase-shifting) as a

function of engine operating conditions. There are four possible types of VCT with DOHC engines:

 

• Intake Only (phase-shifting only the intake cam);

• Exhaust Only (phase-shifting only the exhaust cam);

• Dual Equal (phase-shifting the intake and exhaust cams equally);

• Dual Independent (phase-shifting the intake and exhaust cams independently).

 

All four types of VCT are used primarily to increase internal residual dilution at part throttle to reduce NOx, and to

improve fuel economy. This allows for elimination the external EGR system.

 

With Exhaust Only VCT, the exhaust camshaft is retarded at part throttle to delay exhaust valve closing for

increased residual dilution and to delay exhaust valve opening for increased expansion work.

 

With Intake Only VCT, the intake camshaft is advanced at part throttle and WOT (at low to mid-range engine

speeds) to open the intake valve earlier for increased residual dilution and close the intake valve earlier in the

compression stroke for increased power. When the engine is cold, opening the intake valve earlier warms the

charge which improves fuel vaporization for less HC emissions; when the engine is warm, the residual burned

gasses limit peak combustion temperature to reduce NOx formation.

 

With Dual Equal VCT, both intake and exhaust camshafts are retarded from the default, fully advanced position to

increase EGR residual and improve fuel economy by reducing intake vacuum pumping losses. The residual

charge for NOx control is obtained by backflow through the late-closing exhaust valve as the piston begins its

intake stroke."

Edited September 22, 2016 by Plus 3 Golfer

[ptjones]

From FORD.com CMAX specs compression ratio 12.3 if anyone wants to know. :)

 

Paul

Edited September 22, 2016 by ptjones

[fbov]

This is the last test I did before retiring, with a resulting lack of data from my daily commute since then. This is two consecutive tanks, over the same range of temperatures. Same route, round trip every day with a cold start at both ends. 

 

What's interesting is the pattern of data from 91E0 fuel; note the break at ~ freezing, with a divergent arm reaching higher mileage levels on occasion. It's as though the octane/ethanol didn't matter until the engine temperature at the start of the trip got higher. Then we see high mileages that aren't attained with 87E10 fuel, averaging 12% higher at 50F (no difference at 10F).

 

As to cost effectiveness, I went from $70 in gas every 10 days, to $30/month with the C-Max. The cost differences are small in the scheme of things; I must be a hobbist! 

 

HAve fun,

Frank

[plus 3 golfer]

Snow15 91E0 87E10 Comparison.jpg

This is the last test I did before retiring, with a resulting lack of data from my daily commute since then. This is two consecutive tanks, over the same range of temperatures. Same route, round trip every day with a cold start at both ends. 

 

What's interesting is the pattern of data from 91E0 fuel; note the break at ~ freezing, with a divergent arm reaching higher mileage levels on occasion. It's as though the octane/ethanol didn't matter until the engine temperature at the start of the trip got higher. Then we see high mileages that aren't attained with 87E10 fuel, averaging 12% higher at 50F (no difference at 10F).

 

As to cost effectiveness, I went from $70 in gas every 10 days, to $30/month with the C-Max. The cost differences are small in the scheme of things; I must be a hobbist! 

 

HAve fun,

Frank

What were you paying for the fuels?  When I look on gas buddy, it looks like currently 91E0 is over 25% more expensive than 87E10 in Rochester.  

 

I guess I'll have to do a test with 93E0, currently $2.79 / gallon vs 87E10 at $2.05 / gallon or about 36% more expensive. I'll be heading to Pittsburgh in a few weeks.  I'll fill up with 93E0.   I'll need to get over 54 mpg to break even.  If I get 50% of the needed mpg improvement to break even, I'll be near $5 per tank poorer each time I fill-up.  If I used 93E0 for a year, it might only cost me out of pocket $200 which is no big deal.  But my hobby is golf.  I'd rather buy a new putter even though I have plenty. :)  

[fbov]

Two things.

 

Break-even isn't part of the energy content/mileage discussion. You don't use 93E0 for it's cost benefit ratio. The question was if fuel affected mileage, and the data says it does. If cost matters, buy cheap (but not too cheap). http://www.toptiergas.com/

 

To maximize the fuel difference, you'd want a test with low parasitic losses, as they act as noise in the tests. Generally, highway mileage is lower with these cars because of higher aerodynamic losses, making low speed routes a more sensitive test. My data was a 15 mile commute averaging 30 MPH, over a period of months, so you see both signal and noise. Comparable highway data (from 2013/14) is far less noisy. 

 

HAve fun,

Frank

[ptjones]

A strange thing happened when I filled up with 0E 90 octane the Miles to E read 580 miles instead of 800 miles.  Three hundred miles later it was up to 610 miles to E.  At one point I got the combination of miles to E + miles traveled to 1,000 miles. Ended with 915 miles on Trip Gauge and probably could have gone another 15-20 miles before I would have run out. :)  The only time IIRC this has happen when I used 0E. :headscratch:

 

Paul