so usually i use safeway 87 otane gas, and i get about 100miles per 3.5 gallons. THen i decided to put some cheveron 91 octane in just once, and i got about 130 miles per 3.5 gallons. The driving was exactly the same route, time, almost same traffic. What gives?? Should i alwayus use 91 octane or is something jsut relly weird. Only mondifications i have done is k&n filter and airbong removed.
Nothing is wrong. I have a 98 Z24 and have done my own mileage tests using 87, 89 & 91 octane gas. My car also does better on the 91 octane. Our cars do not need to use the higher octane to prevent 'pinging', but I have noticed that the higher octane, 89 or 91, seems to make my car run better and get better gas mileage.
I live in NM and around here they only have 86, 88, &91 octane. Don't want to be stupid and use 86 since the owners manual states not to use anything lower than 87. Normally I use the 88 octane and when I want to treat my car, I'll go to Sam's club and get 91. This past week, 91 at Sam's club was cheaper than 88 at the downtown stations.
So to get to your question, if you are getting better gas mileage and don't mind paying a little more, use the 91. If you want a happy middle ground, just use middle grade, which I can only assume in your area is 89.
98 Z24
RIP Specks
Its not the octane that makes it go further theres probably an addiditive in the more expernsive fuel that helps clean while you drive. I know for a fact that putting plain fuel above 87 is worthless because the car doesn't need it (stock).Think of it this way:
Cavalier: will run the same with all octanes, unless there are addiditive
Corvette: requires premium fuel, will run @!#$ty with 87 or below requiremenets
Doesn't 91 octane allow the computer to advance the timing furthur than the pinging point of 87 octane thereby raising mpg?
The computer can't sense what kind of gas your putting in, octane affects the detonation of the fuel
The computer uses the knock sensor to advance timing.
is miles per 3.5 gallons a new standard for mileage?
Jacob B wrote:Its not the octane that makes it go further theres probably an addiditive in the more expernsive fuel that helps clean while you drive. I know for a fact that putting plain fuel above 87 is worthless because the car doesn't need it (stock).
I know for a fact that 89 and 91 make my Z24 get better gas mileage and has better pick-up. I know this to be a fact in my car. A guy I work with switched from 86 to 88 here in New Mexico, after I informed him that he shouldn't be using 86 in his 2003 Cavalier, and he stated to me that he can feel a difference and has started to get better gas mileage. So Jacob, there are two examples of proof for ya that it does make a difference. No, you do not have to use the higher octanes in a stock Cavalier, but you can and you will notice a difference.
98 Z24
RIP Specks
yes i understand but the gas that you used was it just plain high octane gas? I know for a fact that most companies add addiditves to their premium gas (ex. Texaco - Techron cleaner), if you buy the high octane gas from Texaco you will be getting better gas mileage for sure because of the addiditve. Correct me if i'm wrong.
I think 86 octane is permissible in some engines at higher altitudes. Check your manual.
The additives in premium fuels are cleaners (detergents) which do nothing to improve the energy content of the fuel. In fact, higher octane fuels are harder to ignite, which is why they are used to prevent pre ignition (pinging). The mpg boost, if you even get one, is from the computer allowing the timing to advance further without pinging (thanks to the signal from the knock sensor). Admittedly, if you have dirty injectors which may prevent as good combustion as clean ones, the detergents in premium fuels may improve mpg and hp too.
I am going to have to try using either 89 or 92. I ususally put 87 in mine. I also have a GTO & it only gets 92 & I have noticed that is get's pretty good gas mileage for being a 5.7L V8!!
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2000 Cavalier Z24 A4 Green Met.
my ecotec gets better mileage on 93 octane also..... i believe its because the ecotec has a 10:1 compression ration (thats considered high compression) and high compression motors require higher octane fuel. but i get better mileage, better performance with 93 and i can get it at a gas staion 2 miles out of town for the same price as 87 in town.... so its all goood....
"Only mondifications i have done is k&n filter and airbong removed."
I don't have that in my 03 Cavalier
Old Wolf wrote:I think 86 octane is permissible in some engines at higher altitudes. Check your manual.
His manual doesn't say anything about higher altitudes. Besides, the higher in altitude you go, the more octane you need to have the gas burn properly. There is less air and air pressure up there at higher altitudes and you need the higher octane for proper combustion.
98 Z24
RIP Specks
Jacob B wrote:yes i understand but the gas that you used was it just plain high octane gas? I know for a fact that most companies add addiditves to their premium gas (ex. Texaco - Techron cleaner), if you buy the high octane gas from Texaco you will be getting better gas mileage for sure because of the addiditve. Correct me if i'm wrong.
Jacob, I get my High Octane gas at Sam's Club. Who knows where they get their gas from. I am careful, since I don't know where they get it, and use fuel injector cleaner in the car about once a month. Car has been running great since I have owned it. It is my daily driver back and forth to work.
98 Z24
RIP Specks
hmm thanks for all the help, i think im going to try safeway 91 octane and see if i get the same results and let you guys know. and i got 3.5 becuase that is the 3/4 full line on my gas guage so pleph!
none none wrote:hmm thanks for all the help, i think im going to try safeway 91 octane and see if i get the same results and let you guys know. and i got 3.5 becuase that is the 3/4 full line on my gas guage so pleph!
but by that reasoning how do you know that everytime you fill up that 3.5 gal tops the tank off. you should trust the gauge completely. the closest to accurate you can do is, fill up the tank completely. reset the trip mileage, and when you fill up again, top the tank, see what the pump says for gallons and divide your trip mileage by that. no if thats what your already doing my bad. but the way i took what you just recently mentioned, you're just put 3.5 gallons in when you get down to 3/4 of a tank.
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no i fill to the top (3 cliks) which is usually around 3.5 gallons
As long as none none uses the actual gallons pumped ie. 3.5...3.45...3.63..etc, he should be OK with his calculation.
