Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 1 month ago

What’s the difference between the 4 gases at the pump? What’s the best for you car?

Regular, premium, mid grade, super

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  • 1 month ago

    Depends on where you go, usually it’s the three prevalent gasoline octanes (87,91,93) and diesel. 

    Now many stations have other fuels too like, E15 (sometimes called super 88), E85, and biodiesel. 

    You need to use whatever your owner’s manual calls for you to use with your vehicle. Some models will even print this on the original gas cap or somewhere else on or near that area. 

    It’s vital you follow your manufactures recommendations for optimal performance of your vehicle as well as the longevity of your engine. 

    Now diesel and gasoline aren’t interchangeable a diesel engine requires diesel and gasoline requires gasoline. 

    You put diesel in a gasoline engine it will at best gum up the engine at worse will destroy the engine outright. If you accidentally put diesel into a gas engine and realize it before turning over the key DON’T turn the key. Call and get it towed and drained by a mechanic you’ll save a LOT of money. 

    If you put gasoline in a diesel it might not turn over at all, but if it does it too will quickly be damaged possibly beyond economic repair. 

    Now gasoline is gasoline is gasoline, I wouldn’t say it’s interchangeable either technically but unlike putting diesel in a gas engine or vice versa it’s not going to quickly cause catastrophic damage. If you put 88 in a vehicle designed for 93 or vice versa it’s not going to cause immediate damage but it could cause damage over time. 

    Too high or low octane can potentially damage your vehicle’s components and even possibly void the manufactures warranty if it’s under warranty, so it’s important to use the fuel the manufacture recommends.

    The octane just tells how much the gasoline can be compressed during the compression cycle before it ignites spontaneously. So using a higher or lower octane than the vehicle requires can potentially damage the engine since the fuel could ignites at the wrong time in the compression cycle. This is what is called “knocking” it’s usually happens when using too low an octane. If it’s too high an octane knocking won’t occur so there shouldn’t be any physical damage but that lead to my next point.  

    Now some insist higher octane results in better gas mileage. This claim is based purely on anecdotal evidence and have never been proven scientifically in a controlled environment, as far as I am aware. Again as I said before gasoline is gasoline, octane simply measures how much compression can take place until it spontaneously combusts. It doesn’t change the fuel, just describes when it will ignite during the compression cycle. 

    Now using a higher octane shouldn’t harm the engine since a higher octane won’t ignite prematurely and cause knocking, but it’s also not intended for the vehicle either. The purpose of higher octane is to be used in vehicles with a higher compression ratio that can’t operate on regular 88 without knocking and damaging the engine. 

    Putting 91 or 93 octane in a vehicle designed for 88 doesn’t change anything at all. It won’t knock either way, so where is the benefit of using the more expansive fuel? Just like 88 it won’t knock, but it does cost you significantly more so it’s usually just a waste of money. Same thing with most fuel additives, octane boosters et al are usually in most cases just a waste of money. 

    Now there are different kinds of detergents and additives used in the different octanes. You’ll see gas stations insisting their brand offers better gas mileage because their blend is superior but read the fine print. It’s something like 5 extra miles per tank of gas. So given a car usually has a tank somewhere around 14 gallons and a truck/van around 20 gallons. You’re talking about a negligee increase in MPG. Maybe .25 to .35 MPG difference. Again leading back to the point I previously made that additives are nothing but a scam IMO except in very rare circumstances when’s dealing with extremely high performance vehicles such as race cars. 

    It’s a no benefit scenario, at best nothing changes at worse over time it causes damage. Why risk it, especially when it’s sole evidence is anecdotal or not done in a controlled environment. 

    Source(s): Driven diesel and gasoline vehicles commercially for almost 2 decades and seen first hand on several occasions the consequences of using the wrong fuel.
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  • 1 month ago

    There was an interesting article in Car and Driver a year ago where they tested four vehicles with the suggested 87 octane then increased to 91 octane. In every one of the tested vehicles, miles per gallon increased when 91 octane was used. If you want to try increasing the octane where 87 is called for by the manufacturer, you'll have to keep accurate mileage records to see if the increase in mileage is worth the extra cost of the fuel. The higher octane works this way: Nowadays every gasoline powered truck and car has an anti-knock sensor which decreases ignition advance when spark knock happens. The higher the octane of the fuel, the less spark knock and more total degrees of ignition advance which increases mileage and a little more power. One of the vehicles tested was a Ford pick-up with twin turbochargers. The truck picked up five miles per gallon using 91 octane fuel. * The higher the octane of the fuel, the cooler and slower the fuel air mixture burns. Go to any gasoline website to verify this fact.

  • Anonymous
    1 month ago

    Different octane.  The type of gas you need depends on your car.   Read your owners manual to see what they recommend.  

    I always put high test in my BMW (as the manufacturer recommended), but someone I know told me I didn't have to do that.  He used regular in his BMW and he never had a problem.  I was afraid the engine wouldn't perform well on regular, so I never tried it.

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  • james
    Lv 7
    1 month ago

    The lower the octain the more power to the fuel but the slower it burns.  So for best millage & easy driving low octain fuel. For fast starts & acceleration High octain fuel.  But you need change the timming on the vehicle. 

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    • Country Boy
      Lv 7
      1 month agoReport

      The lower the octane the faster the fuel air mixture burns. Go to any gasoline website and learn something new today.

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  • Anonymous
    1 month ago

    I'm not sure I've ever seen 4 grades at a gas station.  3 grades, yes.  Sometimes only 2 grades.

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    • None1 month agoReport

      To quote Edmond Dantes, “Perhaps you should get out more.” 

      https://www.youtube.com/watch?v=NzuXQCTycvg

      I mean, if you’ve never seen 4 or more choices at a gas station then either 1) you don’t pay attention well or 2) haven’t traveled around that much. 

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  • 1 month ago

    People keep on asking this question and the same answers get argued over and over. Use what the manufacturer says to use. You don't need to do analytical chemistry to drive your car. Gasoline grades are by octane rating- its ability to resist detonation. Regular is the lowest octane at that pump. Midgrade is a 50/50 mix of regular and premium. Premium is the highest octane at that pump. Usually Super and Premium are the same, but if the brand you're asking about differentiates two grades as premium and super, they have their own recipe fro them. I have not seen 4 separate grades here in California for 45  years or more.

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    • None1 month agoReport

      I do agree that the question of what octane gas to use is one that spurs endless debate. 

      It’s like asking firearm owners what’s the best caliber bullet to carry for self defense. Everyone insists they know the answer and all insist they have “proof” but it’s rarely if ever have any evidence. 

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  • 1 month ago

    You should at a minimum use the specified octane rating by the manufacturer. My vehicle for instance, a truck with the ecoboost V-6 requires a minimum octane rating of 87. If you need minimum 87 and you're in a place that only has 85, 91 and 93, you'd better put in at least the 91 if you don't want any fuel related problems. Otherwise you could use whatever octane rating above the minimum. It may or may not have any impact on your vehicles performance in terms of making it faster, or burning gas slower. My truck uses more gas if I put the 93 premium in it so I just use the 87.

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  • 1 month ago

    It depends on what your vehicle and motor size is. If it's not required to use premium gas use the 87 octane. 

    Source(s): Mitsubishi Master Tech
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  • 1 month ago

    Read about it in your owners' manual.

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  • Murzy
    Lv 7
    1 month ago

    Check the car's manual but it is often on the cover of the gas filler.

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