89 vs 93 Gas
- Thread starter Yo Cheeks
- Start date
carsNskis
New member
Just ran the math with a co workers car on Friday.
Measure your miles achieved on 89 for two tanks, do the same for 93. Take the miles achieved and divide by cost per tank, that's $ cost per mile.
I'd be willing to wager that number is the same for both (or close enough to make you not care which octane you use)
it's not the size, it's how you drive it....
Measure your miles achieved on 89 for two tanks, do the same for 93. Take the miles achieved and divide by cost per tank, that's $ cost per mile.
I'd be willing to wager that number is the same for both (or close enough to make you not care which octane you use)
it's not the size, it's how you drive it....
carsNskis
New member
Here's what we figured on her car:
85oct @ 1.99/gal x 12 = $23.88
28mpg x 12 = 336
Fuel cost $0.071 per mile
x 15k = $1065 per year
91oct @ 2.54/gal x 12 = $30.48
32mpg x 12 = 384
Fuel cost $0.079 per mile
x 15k = $1185 per year
Your results may vary, but not likely very far from this math.
Maybe you 40mpg hyper milers could see some benefit but the RS gearing (and my right foot) keeps me from doing better than 32mpg avg.
I run 91 for the power benefit, I get a little less throttle response from 85 (were also in Colorado above 5k feet so we have thin air to deal with)
it's not the size, it's how you drive it....
85oct @ 1.99/gal x 12 = $23.88
28mpg x 12 = 336
Fuel cost $0.071 per mile
x 15k = $1065 per year
91oct @ 2.54/gal x 12 = $30.48
32mpg x 12 = 384
Fuel cost $0.079 per mile
x 15k = $1185 per year
Your results may vary, but not likely very far from this math.
Maybe you 40mpg hyper milers could see some benefit but the RS gearing (and my right foot) keeps me from doing better than 32mpg avg.
I run 91 for the power benefit, I get a little less throttle response from 85 (were also in Colorado above 5k feet so we have thin air to deal with)
it's not the size, it's how you drive it....
dannyg
Member
OK I'll try it! I've been running right around 40MPG in the rural driving that I do (87 octane/10% ethanol), I'll try a couple of tankfuls of 93...will report back in a couple of weeks. I tried a tank of 91 awhile back with no noticeable difference in power or MPG but I'll give the 93 a try...
Dogz
New member
It'll take nearly 2 tanks of higher octane fuel for the car to change. This is why most people don't think better fuel is worth it, they try it for a tank or two & there is no difference. If you're going to do a comparison between the two you'll need to do the measured runs on your standard fuel then run two tanks of better fuel then do the measured runs on the better fuel. Cars don't just change instantly when you put better fuel in them.
The Champ
New member
I've been down this road before. You can't improve your fuel mileage nearly enough to pay the difference in fuel.
Locally my fuel is $1.879 for 87 octane and 2.339 for 92 octane. Doing the math, I would have to increase my fuel mileage by 25% to break even.
I've been able to hit 40 MPG or better with 87 octane (200 mile trip one way). 92 octane will not get me anywhere near 50 MPG. With 92 octane, maybe 2 MPG improvement.
Unless you have a tune that requires a higher octane, you are just pissing money away by buying a higher octane fuel.
I do STRONGLY recommend buying a quality 87 octane fuel - Top Tier rated.
Locally my fuel is $1.879 for 87 octane and 2.339 for 92 octane. Doing the math, I would have to increase my fuel mileage by 25% to break even.
I've been able to hit 40 MPG or better with 87 octane (200 mile trip one way). 92 octane will not get me anywhere near 50 MPG. With 92 octane, maybe 2 MPG improvement.
Unless you have a tune that requires a higher octane, you are just pissing money away by buying a higher octane fuel.
I do STRONGLY recommend buying a quality 87 octane fuel - Top Tier rated.
carsNskis
New member
Here in Colorado the extra $120 annualy is worth the power to run 91oct.
When I picked up the car it obviously had 85 in it. Pulled like crap out of the hole and the power curve was done at 4.5k rpm.
After 2 tanks of 91 acceleration was more responsive, and power is strong to about 5200.
Went back to 85 for two tanks and response went back to where it started.... I never hesitate to put in better octane now.
Perhaps the Colorado altitude forces the issue where others at lower altitude don't see the same effect (or as drastically)?
it's not the size, it's how you drive it....
When I picked up the car it obviously had 85 in it. Pulled like crap out of the hole and the power curve was done at 4.5k rpm.
After 2 tanks of 91 acceleration was more responsive, and power is strong to about 5200.
Went back to 85 for two tanks and response went back to where it started.... I never hesitate to put in better octane now.
Perhaps the Colorado altitude forces the issue where others at lower altitude don't see the same effect (or as drastically)?
it's not the size, it's how you drive it....
The Champ
New member
carsNskis
When I read your first post, I thought the "85" was a typo and you meant "87".
I just googled Colorado octane ratings - and got somewhat educated.
Your car is designed to run on "87", so I can believe that a performance issue would occur running "85". I understand that the altitude can allow cars to run satisfactorily on lower octane "85" octane regular, but with the changes in elevation that can occur in your state, I still think I'd go with the midgrade (87 or 89).
I have no power curve issues as you describe running 87 here in the cornfields...
When I read your first post, I thought the "85" was a typo and you meant "87".
I just googled Colorado octane ratings - and got somewhat educated.
Your car is designed to run on "87", so I can believe that a performance issue would occur running "85". I understand that the altitude can allow cars to run satisfactorily on lower octane "85" octane regular, but with the changes in elevation that can occur in your state, I still think I'd go with the midgrade (87 or 89).
I have no power curve issues as you describe running 87 here in the cornfields...
dannyg
Member
I finished my test of 93 octane in early December,so here's what happened, I tried three tankfuls of 93 to compare to the 87 that I normally run. I saw maybe...MAYBE...0.5 to 1.0MPG better with the 93. Right at 40MPG with the 87, around 40.5-41MPG with the 93. (I live in a rural area with almost zero stop-and-go.) Subjectively, I might have detected slightly smoother power with the 93 but I can't say it felt like MORE power. Certainly nothing major.
In any case I'm happy with 40MPG. Now that we're into colder weather here in Maine, that will drop a bit. I'm hoping for 38MPG in Jan/Feb driving.
All gas was Shell "Top Tier" with 10% ethanol.
Sorry guys, I'm back to 87. I'm not saying people who see an increase are wrong, just saying I didn't see it. That said, maybe the 1.4T motor is more sensitive to higher octane?? I'm running a 1.8L nonturbo with zero mods.
In any case I'm happy with 40MPG. Now that we're into colder weather here in Maine, that will drop a bit. I'm hoping for 38MPG in Jan/Feb driving.
All gas was Shell "Top Tier" with 10% ethanol.
Sorry guys, I'm back to 87. I'm not saying people who see an increase are wrong, just saying I didn't see it. That said, maybe the 1.4T motor is more sensitive to higher octane?? I'm running a 1.8L nonturbo with zero mods.
The Champ
New member
The manual says 87. There is no performance gain on a stock 1.4T with 89, 91, 93 or higher octane. There also is no fuel mileage gain.
This is assuming that you are using a quality fuel that actually meets the specs.
One of my fuel pump suppliers told me of a fuel test conducted by a research lab in Michigan at the request of General Motors where they actually went out and tested gas at stations all over the country. They actually found gas labeled as 10% ethanol that were actually over 40% ethanol.
Obviously these stations (they were independents) were doing there own "home brew" by calling ethanol plants and ordering straight ethanol to mix with their gas from the refinery. Ethanol costs less than gas, so they were ripping off their customers.
Now if your car is tuned, and the tune is designed for a higher octane, you need to run whatever octane your tune requires.
This is assuming that you are using a quality fuel that actually meets the specs.
One of my fuel pump suppliers told me of a fuel test conducted by a research lab in Michigan at the request of General Motors where they actually went out and tested gas at stations all over the country. They actually found gas labeled as 10% ethanol that were actually over 40% ethanol.
Obviously these stations (they were independents) were doing there own "home brew" by calling ethanol plants and ordering straight ethanol to mix with their gas from the refinery. Ethanol costs less than gas, so they were ripping off their customers.
Now if your car is tuned, and the tune is designed for a higher octane, you need to run whatever octane your tune requires.
lousypirate
New member
I've always ran premium in the sonic. Wife and I agreed on it when we rolled it off the lot. Can't compare it to standard, but big deal at spending a few extra dollars a fill up. I did a whole barrage of tests on my 05 N/A Subie, and landed on continuing to use premium then.
minitrucking02
New member
The car is tuned to run off 87, as it was a car made to get high CAFE ratings. Running a different octane fuel isn't going to help anything- You'd have to re-tune the car to see any advantages, which would most likely lead to a different heat range spark plug and different boost operating pressure. A 93 octane gas is harder to ignite (requires hotter temps) or it can cause knocking/ pinging which gives you LESS power. With that being said I found that my car loves 93 from shell, hates anything else from anywhere else unless its 87. Also, better throttle response under the shell 93, better fuel economy on mobil 87
mja
Site Supporter
Um... my HPtuners which reads the stock tune disagrees with this, which = stock GM programming. Performance gain per butt-o-tha-pants is nill, but there are multiple spark maps written for backing off spark at diff. octane levels.
mja
Site Supporter
A typo?
Stew
Sedans Rule!
mja is correct, there are different spark advance maps for high octane and low octane. You probably won't be able to feel the difference in power, which is probably just a few HP here and there, but you will make more power on high octane if you drive aggressively, or get better economy if you drive conservatively.
It might be easier to think of it in these terms: You will make a little LESS than advertised HP by using low octane fuel, not you will make MORE power by using higher octane fuel.
Again, you will not feel a seat of the pants difference, but it is there. If you are tuned you are playing with fire by using low octane, stock probably doesn't matter much except you may realize a little better MPG with higher octane.
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bluejay
Member
+1 on that , took my car to a tuning shop to ask some questions about octane , buddy hooked my car up to his lap top . long story short , my 2016 rs has 2 fuel maps . one for low octane and one for high octane . my car is stock , i wonder why gm would waste time and money giving the ecu 2 different maps for octane if the car is going to perform the same on 87 or 94 .
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