AAA study concludes "top tier" gasoline is worth the extra cost

By Shawn Knight · 77 replies
Jul 8, 2016
Post New Reply
  1. The American Automobile Association, best known as AAA (pronounced “Triple A”), has concluded that “top tier” gasoline is worth the extra amount of money it costs versus regular fuel. But what exactly is top tier gas and why should you care?

    Developed in 2004, top tier gasoline is a term used to refer to gasoline that has been treated with detergent additives designed to protect engines from carbon buildup and deposits that collect on the intake valves. These harmful deposits can result in a rough idle, hesitation when accelerating, a knocking or pinging sound and perhaps most importantly (at least, in the eyes of the consumer), reduced fuel economy.

    You can typically find top tier fuel at BP, Chevron, Exxon-Mobil and Shell gas stations in addition to other regional chains.

    In its extensive study, AAA randomly selected six fuels from three gasoline sources and commissioned an independent lab to operate engines continuously for 100 hours to represent 4,000 real-world miles. Afterwards, the engines was disassembled, photographed and its key components were weighted to measure carbon buildup.

    On average, engines run with top tier gasolines had 19 times fewer carbon deposits on intake valves, injectors and in the combustion chamber versus regular gas.

    A study of gasoline prices over a 12-month period found that, on average, you’ll pay about three cents more per gallon for top-tier fuel.

    This is the sort of controversial topic that mechanics and gearheads can go back and forth on but the evidence speaks for itself. As for whether or not you should invest the couple of extra pennies at the pump each time you fill up, well, that’s for you to decide.

    Image courtesy issarapong srirungpanich, ShutterStock

    Permalink to story.

  2. LiveResistance

    LiveResistance TS Booster Posts: 85   +64

    A study of gasoline prices over a 12-month period found that, on average, you’ll pay about three cents more per gallon for top-tier fuel.

    I may not be understanding this article completely. Is this taking about name brand gas stations fuel, or the different grades of fuel? (87,89,93). If we are talking about the different grades then where in the world is the top tier only 3 cents a gallon more? Heck, anymore it usually cost at least 50 cents a gallon more.
    mojorisin23, Reehahs and p51d007 like this.
  3. Darth Shiv

    Darth Shiv TS Evangelist Posts: 1,811   +472

    US provides very low grade fuel in general - it is completely unsurprising about these results. To be honest, I thought grade of fuel and carbon buildup was common knowledge?

    87/89/91 in California... their "top tier" is considered regular in Australia and I would imagine Japan and Europe where 98+ octane is common.
    Athlonite likes this.
  4. Axiarus

    Axiarus TS Maniac Posts: 253   +124

    Octane has nothing to do with carbon build up, it is all about compression. Putting higher octane in a car rated for lower octane will do nothing special. It will actually, more than likely, hurt performance.
  5. yRaz

    yRaz Nigerian Prince Posts: 2,308   +1,401

    Why not just use fuel injector cleaner once a year and save money? In some cases, carbon build up is the only reason an engine is still together. This is why people say you don't use synthetic oil in an engine that uses conventional oil. synthetic oil has solvent properties that remove the carbon build up around the gaskets causing imperfect seals. Over time the tolerances in an engine become "loose" and carbon builds up in the leaks.

    I wonder how much money AAA received to pay this? "don't shop at places with competitive prices, it'll ruin your car!"
    noel24 likes this.
  6. Wow,a article about gasoline,I thought it would be about where you could get the cleanest electricity.

    I wonder if those 4000 miles included snow,rain,mountain passes,40+ degree heat and stop start traffic.
    namesrejected likes this.
  7. Camikazi

    Camikazi TS Evangelist Posts: 925   +284

    There is the fact that the US measures octane differently from other countries so our numbers are comparable to theirs just our formula ends up with different numbers. Most of Europe and many other countries use RON to measure octane while the US, Canada and a few others use AKI. Since they measure gas differently the AKI octane numbers come out lower than RON numbers for the same quality gas, because of that AKI 92 octane is about the same as RON 98 octane. You don't have "better" gas, you have the same quality gas just measured in a different way. Don't be so quick to jump to conclusions, you might trip and fall.
    Reehahs, gibbstar, mosu and 2 others like this.
  8. risc32

    risc32 TS Addict Posts: 209   +96

    Yup. R➕ m/2 , if you don't even know what that is, well, you won't be the first to talk on about things you know nothing about on the internet.
  9. risc32

    risc32 TS Addict Posts: 209   +96

    Ok, I see it didn't like my typing. That's r plus m /2
  10. davislane1

    davislane1 TS Grand Inquisitor Posts: 4,736   +3,757

    Alright. But what's the difference with fuel efficiency and which engines benefit? Some cars run terrible with "top tier" fuel. Others run terrible without it.
  11. Darth Shiv

    Darth Shiv TS Evangelist Posts: 1,811   +472

    For higher efficiency or more finely tuned engines, yes you are correct.

    It's not a stretch to say European and Japanese engines are tuned a lot finer particularly in their own markets than in the US. Poor quality fuel and having a system that *relies* on carbon build up means you just have lower efficiency, lower build quality.

    Yes definitely stay within manufacturer recommendations. Too high fuel rating affects ignition timing etc.

    Well for a start I haven't seen 92 anywhere yet so yes, Australia, Japan, Europe DO have readily available 98 RON and California seems to either not have it or very sparsely so my point still stands. Jap and Europe have higher as well.

    Also for the record, I believe you are incorrect and that 93-94 AKI tends to equal 98 RON for the markets I have cited.

    87, 89, 91 AKI seems to be everywhere.

    In the higher grade fuels, it burns hotter and they also tend to put cleansing additives as well, both of which help prevent carbon build-up.
    Last edited by a moderator: Jul 16, 2016
  12. yRaz

    yRaz Nigerian Prince Posts: 2,308   +1,401

    well loosening of the tolerances in an engine is more to do to with the driving habits of the owner, but nice jab there. My whole point is that carbon build up isn't really an issue unless you want to reach 300k.
  13. bea108

    bea108 TS Enthusiast Posts: 34   +9

    Synthetics have evolved to the point that what you're saying is no longer true
    Joe Average likes this.
  14. noc81

    noc81 TS Enthusiast Posts: 79   +29

    Octane is the resistance of fuel to combust under compression, and is only useful in high compression engines (of the sports car variety). You'd know if your car required higher octane, and it's an absolute waste of money using it otherwise.

    Top Tier fuel is just a name referring to brands like Shell, BP, and Exxon that claim to put extra detergents in their fuel, which has nothing to do with octane. Missing from the article, though, is that most of these brands don't put the extra detergents in any fuel with lower than 89 octane, meaning that there is still no benefit while running regular 87 octane.

    Given the fact that they tested 6 fuels from 3 brands, I'd guarantee that they didn't test 87 octane. So their 3 cent point is entirely moot, given that it's 3 cents on top of the extra ten cents you're paying to get 89 octane to begin with.
    SirGCal likes this.
  15. noc81

    noc81 TS Enthusiast Posts: 79   +29

    As far as carbon deposits go... Nyeh..

    It's only really an issue with older cars, and by that I mean early emissions mid-80s old. Nowadays engines use far better ignition control, and you won't find much carbon outside of the EGR system, which typically doesn't get cleaned by gas additives.

    I recently rebuilt the intake of a 00' Saturn SL with 203k miles on it, only carbon I found was in the EGR valve and the cruise circuit of the throttle body -- just enough to throw an error code, though not enough to reasonably affect performance on an ancient car.
  16. ajdal

    ajdal TS Rookie

    From what I got out this article the big oil company's put more better additives in their cleaning the fuel injectors the cheaper gas is lacking those additives. There was no mention of octane.
  17. captaincranky

    captaincranky TechSpot Addict Posts: 12,980   +2,527

    I'm still at a loss to figure out what "octane" ratings, which basically denote how fast the gasoline burns, have to do with to do with its detergent potential.

    Let me know when you figure than out.

    Not to mention you can add those detergents post purchase, by pouring in some "fuel injector cleaner"

    Besides, the next generation of self driving cars will be smarter than their drivers, and know exactly which gas is good for them, and which isn't.
    bea108 likes this.
  18. Darth Shiv

    Darth Shiv TS Evangelist Posts: 1,811   +472

    It's not a jab.

    Australia couldn't import BMW and VW diesels until around 2005 due to diesel grade for example.
  19. captaincranky

    captaincranky TechSpot Addict Posts: 12,980   +2,527

    AFAIK, diesel fuel doesn't even carry an "octane rating", and certainly not one for consumers to scrutinize. The sulfur content of fuel oil is, (again AFAIK), the critical factor with respect to polluting the atmosphere.

    Given the recent scandals regarding fraudulent emissions statistics on VW Diesels, I can't help feeling you'd be better off without them.
    alabama man likes this.
  20. alabama man

    alabama man TS Maniac Posts: 374   +240

    At least after I switched to 98 my car has been running much better. Also they add ethanol made from third world peoples food in 95 here and it's been reported to break engines and is not recommended by manufacturers so there's really no choice anymore as 95 and 98 are only octanes on offer. Maybe bad running on high octane gas is american car thing as you have octanes below 90 and guess at that point you need different type of fuel filters and such.
  21. p3ngwin

    p3ngwin TS Enthusiast Posts: 27   +9

    can confirm, our Australian base fuel is RON 91, then 95, then 98.
  22. alabama man

    alabama man TS Maniac Posts: 374   +240

    I have noticed that with better fuel I drive longer and car works better. I really can't see any reason to buy low grade fuel.
    Seals would be fine if you bought a german car and used the gasoline they recommend, probably 98 octane minimum. The gunk harms the seals. Now I understand why american cars need huge engines with no horsepower, their all so full of **** that by end of their lives 5 liters equate to 1 liter micra engine.
  23. captaincranky

    captaincranky TechSpot Addict Posts: 12,980   +2,527

    I do wish we'd pick one scale to compare octane. You're RON numbers are fairly absurd when compared with the US measuring standard. Our regular is 87 octane. We couldn't even buy a "98 octane fuel" from a pump. You'd have to buy octane concentrate to get those numbers, and pour a crap load of it in to boot.

    Before tetra-ethyl lead was outlawed, you could buy 101 octane gas at the pump. (Which was, IIRC about the same octane as standard aviation gas). With 100 or better, you could run compression ration ratios in excess of 11:1, which after all, is what the octane rating is about.

    Everybody's "gasoline" has methanol in it these days. Get used to it.

    And still, none of this discussion of octane or methanol has one blessed thing to do with the actual topic.

    (And yes, I'm off topic quite frequently, thanks for noticing, and you're welcome).
  24. mailpup

    mailpup TS Special Forces Posts: 7,186   +469

    You are so right. Octane ratings have nothing to do with the term "top tier."
  25. noc81

    noc81 TS Enthusiast Posts: 79   +29

    Of course diesel has an octane rating, it's just super low and pointless for diesel, so they use the 'cetane' number which is a measure of the exact opposite -- how easily a fuel combusts under pressure. Diesel engines don't compress the gas/air mixture or use active ignition, but rather they compress air and then inject the fuel mixture in which combusts under the pressure.

Similar Topics

Add your comment to this article

You need to be a member to leave a comment. Join thousands of tech enthusiasts and participate.
TechSpot Account You may also...