I guess it's a good time to be in the midwest, those prices are just a bit higher than we're paying out here yet. (I think we're still under $2 for 87 octane? Or else we just barely broke that...)
I probably don't need to buy expensive gas; I picked up a probably-irrational belief somewhere that it's a little nicer on the engine (a belief I may have picked up from my first car, a 1979 model). I don't actually think I'm at risk for knocking with 87, but with a 14-year-old car, I'm more willing to believe that things will break.
And on average I buy a tank of gas every five weeks, so it's totally in the noise of car-ownership costs.
Hmm. So I guess the only thing that would be likely to make your car start knocking because it's old would be if the compression ratio increased. And I think that is actually possible if you get carbon deposits in the cylinders.
I'm still curious what kind of car you have that gets 46 miles a gallon. Though now I have a vague recollection that maybe it's some sort of small Honda?
I miss my little Civic Hatchback, which got 40 on the highway on 87 octane (it got stolen and stripped for parts last fall, and is no more.) Now I'm driving my grandparents' old car (they're alive and relatively well but no longer driving.) It's a Toyota Avalon, is huge by comparison, and doesn't get nearly the same mileage. It seems to get about 25 mpg on long trips on regular. The manual suggests that it performs better on 91 octane, though, so I'm experimenting to see if I get enough better gas mileage to make it worth it. The price gap between regular and premium seems not to have proportionally increased as much as the base gas prices, so I guess the more expensive things get, the more likely it is to be worth it.
The carbon deposit thing is what I had read about and that worries me about older cars, though things like that are likely less of an issue with a car that has electronic engine control instead of an old-fashioned mechanical arrangement, like my '79 Datsun.
1989 CRX HF, the ultra-high-milage model where they took out heavy things like the sunroof and rear wiper. 46 is the highway number; I haven't checked straight city numbers in a while... mostly because I always seem to go on a road trip somewhere before I use up a tank in the city. The big downside is that it's only a two-seater.
My understanding is that if the engine isn't a spiffy expensive engine, optimized for the higher octane, the expensive gas is irrelevant. But I haven't heard talk of these carbon deposits.
In general that's true. And I think that with a car not designed for higher octane, the premium gas isn't nicer to it unless it's knocking. And if it's starting to knock (possibly because of said engine deposits, but Honda engines tend to easily last a couple hundred thousand miles on regular, so probably not a problem in this case) then you can probably hear it, and use higher octane for a while until the problem gets too bad.
It's my understanding that in newer higher performance engines, like my current car's, there's a knock sensor, and when the engine detects premature combustion, it advances the spark timing, with some attendant loss of power and efficiency. Some car manuals say that you can run it on lower octane but really shouldn't too often, whereas mine just says that you should use 91 for better performance. So probably my engine is rated for and will last a long time with 87 and slightly advanced spark timing, but this is a case where 91 probably is easier on it in the long run. On the other hand, my car is a '96 with only 35,000 miles on it, and at the 10,000-15,000 miles a year I put on it, I bet it will rust away long before the engine gives.
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I *heart* my 46-MPG car. I also *heart* driving occasionally rather than regularly. So I'm going to keep filling up with 93.
And on average I buy a tank of gas every five weeks, so it's totally in the noise of car-ownership costs.
I'm still curious what kind of car you have that gets 46 miles a gallon. Though now I have a vague recollection that maybe it's some sort of small Honda?
I miss my little Civic Hatchback, which got 40 on the highway on 87 octane (it got stolen and stripped for parts last fall, and is no more.) Now I'm driving my grandparents' old car (they're alive and relatively well but no longer driving.) It's a Toyota Avalon, is huge by comparison, and doesn't get nearly the same mileage. It seems to get about 25 mpg on long trips on regular. The manual suggests that it performs better on 91 octane, though, so I'm experimenting to see if I get enough better gas mileage to make it worth it. The price gap between regular and premium seems not to have proportionally increased as much as the base gas prices, so I guess the more expensive things get, the more likely it is to be worth it.
1989 CRX HF, the ultra-high-milage model where they took out heavy things like the sunroof and rear wiper. 46 is the highway number; I haven't checked straight city numbers in a while... mostly because I always seem to go on a road trip somewhere before I use up a tank in the city. The big downside is that it's only a two-seater.
On the way back the same station was now selling it for $2.03.