Premium fuel...................worth it ?

Discussion in 'Bad Dog Cafe' started by Tomm Williams, Feb 13, 2019.

  1. imwjl

    imwjl Poster Extraordinaire

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    I've been a data nerd on this stuff because the farmer's coop I belong to and COSTCO both 1-1.5 mi from home have good options and prices. Both have the "top tier" seal. The farmer's coop has the E-85, 10% ethanol, and all petroleum. They have 87, 91, 93 and special racing fuel. COSTCO has 87 and 93 octane.

    For my Outback it really did do slightly better with pure gasoline but it cost more to get better fuel economy - a no payoff. At best the pure gasoline was only worth it if I was heading to cabin with roof box and bikes on hitch rack. For my 4Runner a few times higher octane stopped ping. So did doing the scheduled tuneup.

    The VW is barely broken in but as said, I found a test that showed that turbo engine did have more power on dynamometer with higher octane. This makes sense knowing you can blow on the fire. I'm certain a test graphing output from idle to redline included blowing on the fire.

    I'll do same nerd/accountant thing with the VW now. Consider similar weather and wind for a cabin trip and different grades of fuel.

    I do think some of the advertising for that top tier detergent grade is a stretch or is nonsense if you consider the carbon build up issue and engine design. My understanding is all the direct injected engines without additional injector before intake valves are prone to the problem. I digress but also be careful about disinformation or wrong info on some engines. Some have newer rev/gen versions with fuel hitting the intake valves. For the carbon build up issue all my reading says it's blow back and contents of the EGR/PCV circuit that make the mess.
     
  2. beninma

    beninma Friend of Leo's

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    It's never pure gasoline.. does this non-ethanol gas you have available have MTBE in it? We had MTBE here before ethanol.

    Both are used as knock preventers & octane boosters.

    Ethanol results in more power & better emissions, but worse fuel economy.

    The thing with MTBE was it was really really bad for groundwater contamination.

    I have an Outback and it gets crap fuel economy around town, so bad that even a 3-4mpg difference would make a decent difference... it would almost would be worth trying mid-grade if it actually helped. But my Outback is not a Turbo or anything where there's any reason to believe it would help.

    It's easy to forget, the worse economy your vehicle is getting the larger % difference an improvement can be. Changing something to get 5mpg difference on a Prius that averages 50mpg is nowhere near the same as getting a 5mpg improvement on a 15mpg truck/suv.
     
  3. imwjl

    imwjl Poster Extraordinaire

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    I meant the non-ethanol blend.

    The Outback like some other modern vehicles, is really poor at short distance metro driving. A 12 mi round trip I do gets considerably better fuel economy than a 7.5 mile trip I do often. It's worse in cold weather when it tries to run a few hundred RPM faster. OTOH, it's been good for metro boulevard and freeway driving compared to the SUV it replaced. It can be underpowered for loaded fast highway driving and keeping up with traffic drops the fuel mileage by 1-3 MPG.

    My complaints aren't that many. It's a 2013, it's been reliable, and I drive off road 2-7 days a week. It handles ski area service roads signed 4x4 only and sure beats driving a bigger SUV or pickup. Using the adaptive cruise can help your fuel economy. I won't name names but one of my family members gets better fuel economy if they use adaptive cruise as often as I do.

    The Alltrack is sort of a different animal as much as they are both wagons.
     
  4. 2HBStrat

    2HBStrat Tele-Holic

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    I would think that the manufacturer would know what kind of fuel that the car they made should use...
     
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  5. David Barnett

    David Barnett Doctor of Teleocity

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    I remember when people would pour automatic transmission fluid in their carburetor to do the same thing. The huge clouds of pink smoke were highly amusing too.
     
  6. Glen W

    Glen W Tele-Afflicted

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    Top tier brands contain additive packages that at least help clean the injectors in DI engines. Although it doesn't get the back side of the intake valves clean, an occasional Italian Tune-Up is a fun way to do your part. :D

    My GTI will run fine on 87 octane - and I've done it during the winter months. But now that it's warmer, I've moved back up to 91 octane. I'm conscious not to lug the engine anyway, but whatever I can do to lessen the chances of LSPI makes it worth the extra cost, I think.
     
  7. Telenator

    Telenator Doctor of Teleocity Vendor Member

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    Premium gas burns slower than low octane gas.

    Premium is best suited to lower RPM engines with longer pistons strokes because the pistons remain on the downward power stroke longer and the slower burning premium fuel continues to push the piston down for a longer portion of the the power stroke.

    It's that simple.
     
  8. boris bubbanov

    boris bubbanov Tele Axpert Ad Free Member

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    That would be, gasoline with no alcohol in it.

    But well, seems like it doesn't matter, that the alcohol is bad for the motor.

    There's also cars that run better on grades of fuel that tend not to exist. 91 AON; 88 AON, stuff like that.

    Some cars run better on Winter blends, pretty much year round and some run better on the Summer blends. And some cars like Eastern gasoline but a few like the stuff you might find in Nevada.

    Since the manufacturer is not clairvoyant, and cannot predict in advance what fluid will be in those tanks when the customer appears, to fill up, of course things don't turn out right, a lot of the time.

    And I happen to think that some cynical auto manufacturers, assign their cars a need for Premium fuel, to attract a sort of buyer who likes to pay extra for everything. These people for whatever reason, don't complain when the dealer or etc. rips them off. Once you have cultivated a customer base that pays an extra 30% per gallon for fuel, and loses fuel efficiency in the bargain, that person will not beat the stuffing out of the Service Advisor when presented with a bill for $ 3,000. Or when told they must kitty up $ 7,000 when they turn their ride in at the end of the lease. Some sorts of people, just pay when told to and they IMO are excellent for making a profit - if you can grow some of 'em.
     
    Last edited: Jun 30, 2020
  9. DesmoDog

    DesmoDog Tele-Afflicted

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    No it isn't that simple. Higher octane gasoline does NOT control detonation by burning slower. That's a wive's tale that makes no sense when you look at other things used to make engines run better. Dual spark plugs, MSD ignitions, swirl in the intake, all of them speed up the burn. How does slowing the burn down in high performace applications make any sense? In fact if you introduced a gasoline that burned slower, detonation would get WORSE, not better. You want the mix to burn before it has a chance to explode. That means burn if fast, not slow.

    But don't take my word for it, Google technical sources, not car magazines. I've had this conversation countless times over the years so I'll just copy/paste an old post with references;


    I've seen this basic write up on a couple different race fuel supplier sites.
    http://www.whitfieldoil.com/www/docs/171.284/vp-racing-fuel-
    Another link from a fuel supplier
    http://www.pinux-products.com/octane-rating/
    Check out Section 6.3 of this university paper:
    http://blizzard.rwic.und.edu/~nordlie/cars/gasoline.html
    Last part of section 7.4.
    http://www.repairfaq.org/filipg/AUTO/F_Gasoline7.html

    Sunoco Race Fuels says this:
    http://www.racegas.com/article/10
    Any opinion can be supported by links to internet sites. But it also makes no sense that a slower burning mixture would be better for controlling detonation. Flame fronts, even fast ones, are a controlled burn, detonation is an explosion.
     
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  10. doctorunderhill

    doctorunderhill Tele-Meister

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    as someone who many years ago worked in the lab of a gasoline refinery-formulating blends for octanes, running (or trying to run)/calibrating/rebuilding ASTM Research and Motor octane engines( one from 1929 and the other from 1932) and all the pursuant physical testing- I can say you have covered the bases extremely well.
    my compliments.
     
  11. beninma

    beninma Friend of Leo's

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    I have the same Outback (2013 2.5L) and totally agree with you. My drives are short (<10 miles) and it gets 20-22mpg most of the time on my commute, and more like 18-20mpg in the winter. No matter which way you cut it though I think that is horrible on a car that managed to get a 24mpg rating in the EPA test. If anything has been done on new outbacks my guess is they figured out how to get the engine to heat up faster. The issue with the outback compared to inline-4s or inline-6s/v-6s as far as I can tell is the H-style engine takes longer to warm up due to it's shape and orientation.

    The H-style/horizontally opposed engine is great for low center of gravity but bad for just about everything else.. heavier, more parts, more likely to have issues with the gaskets since they're vertically oriented, takes longer to reach operating temperature, etc.. It is ironic this style of engine only appears on super high performance very expensive sports cars other than Subaru.

    It also seems highly affected by wind due on the highway due to poor aerodynamics (body cladding) and the ground clearance.

    The last 2 weekends I had done about a hundred mile drive 2x out and back. On the out we had the prevailing wind, on the back we were fighting the wind. The first weekend it was windy and it could only get 25mpg (all highway zero traffic) with 1 bike on the roof. The 2nd weekend it was not windy and the car got 28mpg going > 70mph with the bike on top which was great as far as I'm concerned considering the bike.
     
  12. imwjl

    imwjl Poster Extraordinaire

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    It was funny to hear my daughter praise the fuel economy but she was driving a much older car that needed some work.

    I've only had it for one warm month but see how fast the VW EA888 gen 3 with exhaust manifold integrated in the head warms up. Water temp is high right away. Friends with other recent generation vehicles have complained about how poor they all are with short distance driving and especially when it's cold. One who's a mechanic said the cold engine tune is also part for catalytic converter getting the right temperature.

    Oil temp builds slower. I mostly can't complain about the Outback. When it gets 19-22 MPG my 4Runner was getting 15-17 MPG. My old gasoline pickups were worse.

    So far a fairly often and consistent work trip I do has the VW Alltrack getting 4-5 MPG more than Outback and it can still accelerate when the Outback just makes noise. I did test a 2020 Outback. You'll pay for it but the turbo engine solves one issue. CVT seems slightly improved. My mother in law has 2012. Earlier and later CVTs do behave differently - not much but differently. Outback is still a superb vehicle for what we do that's urban and rural.
     
  13. tery

    tery Doctor of Teleocity

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    110 Octane

    [​IMG]
     
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  14. beninma

    beninma Friend of Leo's

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    Everything with the modern engine changes is about getting them to heat up *faster* not slower. They try to get them to heat up ASAP because they can't run the engine at its cleanest when it's cold. Modern Hondas have done all this stuff with integrating the manifold and moving the catalytic converter as close to the block as possible too. I think some cars even have mechanisms to heat some of the components.. not sure I am remembering that correctly though.

    The VW All track could be doing better if it's an AWD that disengages completely vs the Subaru design which is always engaged. Pretty much every one of the "Part time AWD" systems has the potential to be better on fuel economy but the performance of the full time systems is better.
     
  15. JIMMY JAZZMAN

    JIMMY JAZZMAN Tele-Meister

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    Here's the juice. Newer vehicles only. High test: Gas mileage lower, but engine performs optimally.
    Low test: Mileage a tad better ($$$$$$ wise) but you'll be in the shop, much sooner with various and sundry
    problems with your vehicles engine. I guess it's a pay now or pay later proposition, which is a decision based
    on short or long term equities.
     
  16. imwjl

    imwjl Poster Extraordinaire

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    I didn't catch the daughter comment earlier. Recent months have had all the kids home and have been shaking up who's driving what. I'm always beating my daughter's and wife's average in same vehicles. Now my daughter is using the Subaru "EyeSight" more. Her bother does. We have our technology haters here but I have proof that cameras tied to computers are better than average drivers.

    Also funny is I filled the new VW and my wife mostly drove it since. I got to Milwaukee yesterday surprised by only 1/4 tank. Every time she drives it she tells me "It's SO fun." and something like "They're wrong when the dash tells you to shift." or "It goes like the old rocket wagon or Mustang when you hear the turbo". I believe the stereotypes for males as lead foot are wrong.

    On RPM, I've had fun being a nerd and following how the modern engines have changed. We still have our Model A in the family. For a time I was into Ford performance stuff. All the modern engines do better at lower RPM. Variable valve timing with modern electronics is done differently across manufacturers but puts what used to be different engine designs in the same package. Direct injection for gasoline more like diesels work allow better characteristics. The fun RegularCars youtube reviews also remind how we have 5 - 8 speed transmissions or CVTs keeping the engine where it's happiest or best when we used to have 2, 3 or 4. IIRC, there was a vintage 50s/60s GM that was one speed automatic.

    Next up is far more all electrics and I'm certain we'll have plenty of complaints with those too including crushing egos and tribal behavior not just with that change but with who dominates. I almost did it a month ago. I could not get myself to spend on a Model Y and didn't like the alternatives.

    :)
     
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  17. boris bubbanov

    boris bubbanov Tele Axpert Ad Free Member

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    In some instances.

    The duty to add your own additives, comes with using lower octane fuel. Some like Chevron's additive; some like Seafoam, but for regular use I like Lucas' Fuel Treatment. This stuff lubes and conditions the fuel and helps tame the alcohol and appears to me to mitigate most of the issues with low octane fuel. Buying stipulated Top Tier helps a whole lot in some markets and in others, the fuel is all about which refinery produced it or which kinds of cat-fuel or crude they have best access to. Which additive one use may depend on your choice of car brand or type of motor, what climate you live in, and what is going on at the refinery that usually supplies you.

    Maybe your condition doesn't apply to me: My cars are 1996, 2001, 2002, 2003, two 2004s and a 2006. Not old really, but these are not ones that use 0W16 oil and so forth. Come to think of it, all but one have iron blocks. They're durable; maybe they're not the "newer" ones you speak of.

    If the added sales price of premium was something like 10-15% I'd probably use it just about all the time. The differential between high and low octane is small in California and so I use premium there. But there's so many places in the eastern 2/3rds of the USA where the "premium" for premium is 35%. I think that money is better spent, buying additives and using them often, rather than spending an extra 75 cents per gallon.
     
    Last edited: Jul 1, 2020
  18. imwjl

    imwjl Poster Extraordinaire

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    Yes. Subaru does it via the raised RPM and fuel delivery. The VAG EA888 gen 3 in many Audi, VW, Skoda and SEAT integrates exhaust manifold in the head.

    I believe you need to define newer. They've been better with and completely designed for lower octane fuel for several years now. Honda and VW have shipped a whole lot of turbocharged engines that work fine all over the world. Not just performance engines.

    The "top tier" designation is a detergent standard that is important. High test meaning octane is as it's always been. That is about how much compression before detonation.

    The issue of carbon on intake valves is also one where you have to be careful about rumors and nonsense. There are some direct injection designs where there is no fuel crossing the intake valves. I know for sure there are Ford, Honda, Toyota and VW designs that address that. They are still direct injection engines but have a port or throttle body style injector that in essence washes the intake valves with fuel.
     
  19. imwjl

    imwjl Poster Extraordinaire

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    Now and probably for 10 years or more they design major items and vehicle systems for the whole world. There are a lot of niche vehicles but engines are very same world wide. What people buy a lot of is often identical or nearly identical stuff world wide.

    With cars, a gapminder mindset is required for those who know the Roslings. I have fun asking some I know who the biggest automakers are and what the top selling vehicles are. Very often they are stuck not knowing that. IIRC, a lot of this standardization started with some European models same as US, a Boeing CEO going to Ford, and the Corolla and Golf positions as top sellers world wide. China as an auto maker and market is another big influence.
     
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  20. Telenator

    Telenator Doctor of Teleocity Vendor Member

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    Detonation is NOT slow burn. It detonates, which, to my understanding means basically explodes.

    My response was in an effort to offer a simple explanation of why high octane fuel is beneficial to some stock engines over lower octane fuel. And it is. I didn't mean to get all involved in the deep theory of cam lift, duration, head shape and combustion chamber vortex patterns, compression ratios and a whole bunch of stuff that which, while very interesting, is way more information than is necessary to a guy with a family car or stock motorcycle wondering if there is an advantage to using high octane fuel. The simple answer is, "yes," in some cases there is an advantage.
    Thank you for the thorough information concerning this topic.
     
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