Regular Vs. Premium Fuel

My bad...you are correct. I could have sworn I read an article saying Exxon had bought them out.
 
I would say negligible difference. The car mentions 91 as the required octane level in the manual. I'm surprised you can get 91 and 93 in your area. Usually it's one or the other from what I've seen.
 
webby said:
I would say negligible difference. The car mentions 91 as the required octane level in the manual. I'm surprised you can get 91 and 93 in your area. Usually it's one or the other from what I've seen.
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All the top tier stations and gulf all have 93 and not 91 here it's strange but convenient. Found a shell right by my work that has 93 for the same price as cheaper stations. I use an app called gas buddy it's incredible.
 
They only sell 87, 89 and 93 here. I fill a full tank with 93. When I reach a half tank I top off with 89. Then I alternate every half tank between 89/93. I keep track with a book I have in the glove box. If I ever have to fill up more than half a tank I just run it to almost empty and fill up with 93.

Half 89 and half 93 evens out to 91, which is what is recommended. I've done this for almost 10k miles and haven't had any problems. I redline the car frequently as well. It doesn't save much over just going straight 93, but every it's better than nothing.
 
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I normally see a huge different when putting 91 in an 83 car. The gas mileage goes up and you can feel like the "car has its youth again". I don't know if its a good thing, but it feels great to have better mileage and the kick when you want to floor it. <--- I really think this messes with your car when you switch octanes or use a different oct that isnt preferred, I only do this on rent a cars and my jobs vehicles (screw them lol)

My mom swears the car is better when you put 91 in her 2012 Nissan rouge, but If you can put in your 2 cents I will take it to mind.

I'm more interested in the best brand to buy. I go to 3 stations, Valero, Hess, Shell. Valero doesn't seem to give great mileage, but its the cheapest. If fill up with hess my gas lasts longer, but doesnt have the push as if i fill up with shell. Shell seems to be just as good as hess with mileage, with giving me the push, but its like 5-10 cents more a gallon.

I normally do 1.5 tanks on gas and 1 tank on expensive stuff. Should I do all the expensive stuff? It doesnt really hurt my wallet, but its a pain to hess or shell that isnt price gouging
 
You could do the math pretty easily. Say you are paying 10 cents more per gallon on a 13 gallon fill up. You just spent 1.30 extra on that tank. Say you get 2 extra miles per gallon on that brand of gas. On 13 gallons, you'd travel 26 extra miles (13x2)...for a cost of $1.30. Say you normally get 26mpg....that's a pretty cheap gallon of gas at $1.30. Multiply that savings over a long period of time/miles. If you get better than 2mpg on that brand, your savings are even greater.
 
It is possible the ignition system could be in need of a tune-up (timing is advanced - not an issue on coil-pack Civics, or other issues). The higher octane fuel can mask minor problems that would otherwise lead to some detonation with regular-grade fuel.
 
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I'm used to running premium simply because of the various German, turbocharged or high compression engines. Yes most modern engines have an octane sensor which in turn adjusts timing etc to prevent knocking and pinging. However if the manufacturer recommends Premium it's for a reason. Why would they say that if people are concerned about fuel prices? They take a risk on losing sales doing that so apparently it's for a reason. I learned the hard way when I tried to skimp with my 99 Integra GS-R. I put about 10 bucks of 87 in it and that B18C1 pinged its *** off all the way to the next gas station where I filled it with 93. Skimping on $3-4 is not worth damaging your engine. I am a Service Advisor and I can promise you that manufacturers take fuel samples from the tanks of cars that come in under warranty for engine problems.
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My reporting location got changed at work to 160 miles a day. I did 3 weeks of driving all highway with the 93 shell prem. I now have done the past four weeks on 89 shell. There is no change what so ever in mpg at all and no noticeable power loss. The conditions are the same every day. There is never any traffic at 3 am so cruise takes me down and I keep it between 60-80 on the ride home. I hole shot almost every day getting on the highway to see if I can get to a higher speed by the time I hit the mile marker and always the same!
 
1flySi said:
I am a Service Advisor and I can promise you that manufacturers take fuel samples from the tanks of cars that come in under warranty for engine problems.
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Recommended means not required therefor they can not deny you warranty work
 
I had a G37 as a rental car... I accidentally put in a tank of 87 cause I just didn't think about it. I put 93 on the next one. There was a noticeable difference in the power the car had and how fast it would let you accelerate. The engine definitely compensated.
 
Brooksie365 said:
There is no change what so ever in mpg at all and no noticeable power loss.
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Maybe not noticed by you, but probably still there and possibly able to be noticed by someone else. Perhaps you just want to believe so badly that there is no difference that you are just not noticing... Try 89 at a few different gas stations, then dyno the car. I guarantee you will make less power than someone with identical car running 91+.

It is well known that retarding the timing decreases power. The engine retards the timing to compensate for the lower octane. This is fact.

OR maybe even you are really lucky and the gas station's 89 octane is actually higher than that and enough to cause no problem. The octane rating on the pump really is just an estimate and different factors can contribute to it being wrong by a couple of points, and not always in the negative direction.

Plus you are cruising. Pinging would be most increased during acceleration. How can you comment much on performance when you're cruising around 99% of the time (I am guessing, since you mention 3AM and being on cruise)? That's not performance-demanding driving at all
 
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trustdestruction said:
Maybe not noticed by you, but probably still there and possibly able to be noticed by someone else. Perhaps you just want to believe so badly that there is no difference that you are just not noticing... Try 89 at a few different gas stations, then dyno the car. I guarantee you will make less power than someone with identical car running 91+.

It is well known that retarding the timing decreases power. The engine retards the timing to compensate for the lower octane. This is fact.

OR maybe even you are really lucky and the gas station's 89 octane is actually higher than that and enough to cause no problem. The octane rating on the pump really is just an estimate and different factors can contribute to it being wrong by a couple of points, and not always in the negative direction.

Plus you are cruising. Pinging would be most increased during acceleration. How can you comment much on performance when you're cruising around 99% of the time (I am guessing, since you mention 3AM and being on cruise)? That's not performance-demanding driving at all
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performance change sure maybe there is some that i cant tell and maybe you could. i hope you didnt take this as its better performance. i was filling my car every two days to three days putting in gas that was 23 cents more per gallon to just burn it cruising on the high way. i tryed a couple tanks of 89 and it seemed to run fine for what i was using it for. i still had my fun at stop lights and on ramps and i noticed no difference. i use shell so i was going from 93 to 89. this was just my point of view from a commuter.
 
Brooksie365 said:
performance change sure maybe there is some that i cant tell and maybe you could. i hope you didnt take this as its better performance. i was filling my car every two days to three days putting in gas that was 23 cents more per gallon to just burn it cruising on the high way. i tryed a couple tanks of 89 and it seemed to run fine for what i was using it for. i still had my fun at stop lights and on ramps and i noticed no difference. i use shell so i was going from 93 to 89. this was just my point of view from a commuter.
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Nah, I didn't take it as you saying better performance with 89. I understood.

Is 89 regular where you are at? Here and many other places it is 87. So, to me, you're running mid-grade. Definitely not going to be as noticeable as running regular 87 which is the standard in many places (although I don't know exactly where else 87 is regular, i'm in FL… I do know that it's regular in other states too though, can't remember which ones). That's because the engine doesn't need to compensate as much by retarding ignition timing with 89 since it's only 2 octane points below the recommended 91… it's not going to ping as much as 87 would.

Maybe try some other gas stations with 89 octane for more sample size?


So, maybe 89 is "okay", but I wouldn't run it in my K24 personally. And I definitely would steer anyone else away from using 87.
 
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trustdestruction said:
Nah, I didn't take it as you saying better performance with 89. I understood.

Is 89 regular where you are at? Here and many other places it is 87. So, to me, you're running mid-grade. Definitely not going to be as noticeable as running regular 87 which is the standard in many places (although I don't know exactly where else 87 is regular, i'm in FL… I do know that it's regular in other states too though, can't remember which ones). That's because the engine doesn't need to compensate as much by retarding ignition timing with 89 since it's only 2 octane points below the recommended 91… it's not going to ping as much as 87 would.

Maybe try some other gas stations with 89 octane for more sample size?


So, maybe 89 is "okay", but I wouldn't run it in my K24 personally. And I definitely would steer anyone else away from using 87.
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As soon as I'm not driving 160 miles a day premium will be back in it
 
Brooksie365 said:
around a dollar a day but that makes a significant difference in my situation right now
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Where I'm at its like 10 cents more for the next grade above 89 (91 or 93, both at least the Si's recommended octane).

160 miles a day at say approx 32 mpg highway = 5 gallons a day. So 5 gallons times the difference in price (10 cents) = 50 cents. You should get better than 32 mpg though, more like 34 mph (that's what I get while cruising all highway).

Anyway, that's how I got 50 cents or less. I could be wrong about your regions gas prices though, but i have always seen about 10 cents higher for each grade of gas incrementally. But if you're cruising all highway and not getting 32+ mpg then something is wrong, as 34 ish is about what everyone is getting for highway in an Si. The EPA numbers are way off.

Sorry to hear about your situation though, hope things get better for you :)
 
Brooksie365 said:
Recommended means not required therefor they can not deny you warranty work
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In the case of our Si's no they cannot. However vehicles that state Premium Unleaded Required does apply. Our cars will run on 87 however theres a noticeable difference when you do.
 
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