How important is the octane of your gasoline?

[SteveMo600]

Just wanted to get some more info on the octane of gasoline. My car says that premium fuel is "recommended" but not essential. Does anybody know how vital it is to use high octane fuel if it's recommended. I know that if a car needs high octane fuel then you'd be dumb not to put it in. I also heard that if your car just needs regular fuel, then it's a waste to use higher octance fuel. Does it have a big impact on performance or fuel economy etc.?

[ZorroAMG]

Do you care about your car? If so, use nothing less than mid grade 89 octane fuel. What's 3 bucks per tank to upgrade to 91(92 or 94 @ Husky) really?

[GTS Jeff]

Originally posted by SteveMo600
Just wanted to get some more info on the octane of gasoline. My car says that premium fuel is "recommended" but not essential. Does anybody know how vital it is to use high octane fuel if it's recommended. I know that if a car needs high octane fuel then you'd be dumb not to put it in. I also heard that if your car just needs regular fuel, then it's a waste to use higher octance fuel. Does it have a big impact on performance or fuel economy etc.?

well uve answered your own question there buddy.

[Lo)2enz0]

in my golf i only put in mid grade and on the odd occasion 91 grade. keeps your car running better and you get more km/tank. With the ca18det i only put in 91 grade and nothing less. it really makes a difference in the long run and an extra couple bucks per a tank is better than what will happen down the road.

laurier

[Weapon_R]

Anything higher than the required amount of octane fuel is a waste of money. If your car requires premium, use it. If it doesn't, you can get away with mid or regular. `

[SteveMo600]

Originally posted by Weapon_R
Anything higher than the required amount of octane fuel is a waste of money. If your car requires premium, use it. If it doesn't, you can get away with mid or regular. `

That's exactly what i heard. But my car says that it's recommended. Now is it a really good idea to use premium? What will happen if I put in regular or mid-grade? Will it effect my fuel economy and performance quite a bit? Does it do long term damage?

[spike98]

Isnt octane proportion to the chance of detonation? Like more octane, the more the risistance the fuel is to detonation and knocking?

[oddjob]

You're risking detonation if your car is turbo.

['93 SR-V]

Most modern cars will adjust to the octane of the fuel you're using. (I.E, if 91 is recommended, you will get the best results with it, but if you use 87, the car will adjust to avoid damage.) I'm not sure exactly what changes, in my manual it says something about retarding the timing or whatever, but it does it on it's own.

That being said, I find I get an extra 50 or so km's a tank when I use premium over regular (manual recommends premium), so the extra price is made up via the extra km's.

[CokerRat]

SteveMo600: higher octane ironically has LESS energy per unit than lower octane. This is because the higher-octane components that get added to straight-run gasoline have very low heating values (eg. ETBE). So you can safely ignore any claims that higher octane somehow gets better fuel mileage. Exception: if the engine can automatically advance or retard timing AND the engine is damaged and therefore pinging with the recommended octane, then higher octane will help. Other exception: to entice people to buy higher octane, many refiners add more chemical additives/detergents to higher grades of gasoline. Used regularly, it might be true that the car runs better as a result of the additives.

[GTS Jeff]

Originally posted by SteveMo600


That's exactly what i heard. But my car says that it's recommended. Now is it a really good idea to use premium? What will happen if I put in regular or mid-grade? Will it effect my fuel economy and performance quite a bit? Does it do long term damage?

yes.

[Weapon_R]

Originally posted by SteveMo600


That's exactly what i heard. But my car says that it's recommended. Now is it a really good idea to use premium? What will happen if I put in regular or mid-grade? Will it effect my fuel economy and performance quite a bit? Does it do long term damage?

If its recommended, its a good idea to use it.

Will Premium decrease fuel economy? Yes. Will it do any long term damage? Not really.

[X_plorer]

Can possibly make the engine knock. I always ran premium in my civic because I thought it got better mileage. Honda told me the civic can't tell the difference between the grades. The prelude ONLY gets premium, never tried the cheap stuff there. My bike also only ever got premium, wouldn't want to think what would happen with regular and a high rpm sport bike engine. Out in Vancouver before you get on the ferry they have a chevron(?) station I think, the octane on their premium is like 94 or 95 or something crazy high for out of the pump fuel.

[googe]

its actually worse to put in a higher grade than recommended, because then you just get unburnt fuel.

however if your car is designed for it, it will advance timing to take advantage of the higher octane. in this case you will get better mileage by using premium.

otherwise, youll get slightly worse mileage using premium.

and if you REQUIRE it, and you put in like 87, youll probably destroy your engine

[kiwi]

It also kinda depends on the car. On some cars, you will notice a difference if you use premium gas, even if it wasn't recommended, but on others, you wouldn't notice anything & it'd be a waste, kinda.

We use premium gas on all our cars!

[MM93]

Demystifying Octane Ratings


In general, three grades of gasoline are available in the United States: regular (AKI = 87), midgrade (AKI = 89) and premium (AKI = 91 to 94). The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes. Motorists whose cars require 91 octane fuel may find themselves at filling stations that offer only 89 and 93 octane, but nothing in between. In these cases, the options are to pay more for the 93 octane or to fill the tank halfway with 93 and the rest with 89. The resulting gasoline mixture, just like the average of their two AKI numbers, will equal 91 octane.

A gasoline’s octane rating quantifies its resistance to knocking and pinging. These two sounds are caused by abnormal combustion, which robs power and can damage an engine. Knocking and pinging are basically the same thing; knocking is louder and represents a more serious condition. When they occur, it is during acceleration, though higher engine speeds tend to drown them out. Knocking sounds like someone repeatedly rapping the engine with a hammer, and the quieter pinging resembles marbles being shaken inside a tin can.


Most gas stations offer a choice of three unleaded fuels, each with a different octane rating: 87, 89 or 93. Which one is right for your car? That depends on the type of engine you have.

Many conditions in the engine itself can cause or promote combustion anomalies, but when all other factors are equal, gasoline with a higher octane rating is more resistant to knocking and pinging than a lower-octane fuel. So why doesn’t everyone just use high-octane gasoline? Because it is more expensive, and there is no advantage whatsoever in using premium gasoline in a car that doesn’t specifically require it. At one time, only premium gasoline included additives that prevent fuel-injector clogging; now, all grades are basically the same in this regard.

If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.

Your vehicle’s owner’s manual usually recommends an octane rating in terms of an Antiknock Index (AKI), which also is posted on gasoline pumps. The AKI is the average of two ratings determined in a laboratory: the Research Octane Number (RON), which corresponds with low-speed, mild-knocking conditions, and the Motor Octane Number (MON), which covers high-speed, high-temperature knocking conditions and part-throttle operation

[rage2]

For normally aspirated cars in Calgary, you can go down 1 grade from what the manufacturer recommends because of our elevation. If 91 is recommended, you can go 89 and still maintain the same agressive timing. Cylinder pressures are quite a bit lower compared to sea level, and the octane requirements are lower. Save money and get better fuel economy.

[SteveMo600]

Originally posted by rage2
For normally aspirated cars in Calgary, you can go down 1 grade from what the manufacturer recommends because of our elevation. If 91 is recommended, you can go 89 and still maintain the same agressive timing. Cylinder pressures are quite a bit lower compared to sea level, and the octane requirements are lower. Save money and get better fuel economy.

Since my car "recommends" premium, I can put mid-grade in it and it should be ok? Does that mean that it would be a waste of money to put in premium?

[Kaos]

Originally posted by SteveMo600


Since my car "recommends" premium, I can put mid-grade in it and it should be ok? Does that mean that it would be a waste of money to put in premium?

Its only 2 cents more than octane 89, why not pay for something better?
I put in oct. 94 and I dont need it but its only 2 cents more than 92.
You only really save a couple bucks.
Unless you need that couple a bucks for lunch money or something,
Go with a lower grade.

[Moe Man]

my machanic said that is doents do anything, but i just drove a cadillac STS and it keeped boging out and driving a bit rough, and i asked the owner if he uses permium and he says no. i look at the dash and it says PREMIUM FUEL ONLY

so in my case.....if it says it do it