Premium Gas or Mid Grade??

Yep, I still hate this thread.
Arguments over a difference of $6-12 a tank is ridiculous. If you can't afford it, I'm sorry to say that you bought the wrong vehicle.
This isn't a question of whether or not the Si will run fine on regular or plus; IT WON'T. Buy premium only and end this silly discussion.

That is all. Have a great day everyone!
 
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KennyGS said:
Top tier fuel sellers - as listed by Honda (and others) > http://www.toptiergas.com/index.html

​
USA
76 Stations
Aloha Petroleum
Chevron
Conoco
CountryMark
Entec Stations
Exxon
Hawaii Fueling Network (HFN)
Holiday Stationstores, Inc.
Kwik Trip / Kwik Star
MFA Oil Co.
Mileage Stations
Mobil
Ohana Fuels
Phillips 66
Quik Trip
Rebel Oil
Road Ranger
Severson Oil
Shell
Texaco
Tri-Par Oil Co.
U.S. Oil

Canada
Chevron Canada
Esso
Petro-Canada
Shell Canada
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I have been to around 10 gas stations on this list and I see the stations in which my cars perform the best were when running shell, mobil and maybe exxon gas.

I use Hess and the Velero when I want to be cheap but my gas mileage sucks, so its like im throwing $ away.
 
webby said:
In his case, his work won't compensate him for anything but regular gas. That's his issue....and he's trying to get around that.
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I don't understand. He said:
njhustler said:
Seems like im up shits creek. Every car that i am interested in recommends premium fuel , SI , wrx , focus st ect. The problem is my company now reimburses me for mileage , so I can use any grade of gas that I choose.
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So what is the issue here?????
 
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The issue is that I am starting with a new company in 2 weeks and they give gas cards instead of reimbursing mileage. They only allow regular fuel to be purchased. Ive wanted an Si for a little while now so I guess I will be a guinea pig using regular. Ive always used premium fuel in all my vehicles because the extra cost isnt much and I know they run better on it. Like my current vehicle , 2004 Honda Accord exl v6. It says in the manual to use regular , but Ive used premium fuel in it since day one. According to honda engineers that designed the j30a4 , using premium fuel gives it an extra 10hp and 10 ftlbs due to the computer adjusting for the higher octane. If using regular in a si gives the reverse effect , I can live with that. Alot of the cars that recommend premium fuel say that regular fuel is ok , but you will not get the full rated hp/tq out of the engine.
 
njhustler said:
The issue is that I am starting with a new company in 2 weeks and they give gas cards instead of reimbursing mileage. They only allow regular fuel to be purchased. Ive wanted an Si for a little while now so I guess I will be a guinea pig using regular. Ive always used premium fuel in all my vehicles because the extra cost isnt much and I know they run better on it. Like my current vehicle , 2004 Honda Accord exl v6. It says in the manual to use regular , but Ive used premium fuel in it since day one. According to honda engineers that designed the j30a4 , using premium fuel gives it an extra 10hp and 10 ftlbs due to the computer adjusting for the higher octane. If using regular in a si gives the reverse effect , I can live with that. Alot of the cars that recommend premium fuel say that regular fuel is ok , but you will not get the full rated hp/tq out of the engine.
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DO NOT put regular in an Si. webby's post bears repeating:

webby said:
from the manual -

2.4L engine models
Unleaded premium gasoline, pump octane number 91 or higher

Use of a lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
Use of a gasoline with a pump octane less than 87 can lead to engine damage.
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Also, as I suggested earlier:

squiggy said:
Holding more gas wouldn't be the issue I'd be concerned with when arguing discussing this with the employer. He could just go out and buy a truck that gets 16 mpg as opposed to the Si with 28 mpg. I know as an employer I would rather pay the $3 a tank instead of 75%+ more per mile.
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The gas card should not be able to prevent you from buying premium.

I googled this info about the J30A4 and read some posts where people said someone dyno'd it and no increase was gained by using premium. Never did find the actual post with the dyno info though, although I didn't look very long.

Now, regarding working in the opposite direction, it is not that simple. If it were the same case, then Honda would recommend regular fuel in the Civic Si. They know using premium is a deterrent to potential buyers so why would they intentionally scare them away for the hell of it?

Let's start with the basics.

J30A4 - 10:1 compression ratio
K24Z7 (Civic Si) - 11:1 compression ratio
K24Z7 (CR-V) - 10:1 compression ratio

The higher the compression ratio, the higher the compression, of course. In the words of Wikipedia, compression "represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity."

The higher the compression ratio, the more pressure in the combustion chamber. Octane is the measure of a fuels resistance to combustion, or resistance to burn. Under the higher pressure/compression in the Civic Si's K24Z7, 87 octane fuel does not have enough resistance to burn to prevent it from combusting irregularly, ahead of the clockwork of the engine, or out of time... this is called pinging or knocking and can & will cause engine damage

To help prevent this knocking or pinging from occurring, the computer retards the ignition timing. This retarded ignition timing is the reason for the lost power and efficiency - not the lower octane itself. However, this is a band-aid and does not truly fix the problem... pinging/knocking will still occur, although less than it would if the computer did not adjust the timing, because the physical pressure in the combustion chamber remains the same and the computer cannot change the physical properties of the piston and cylinder. Ultimately, you will experience engine damage.
 
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You do make a good point Squiggy . I guess I can speak to my soon to be employer about this issue. Maybe I can have them set a fill up limit , say 50 bucks and maybe get almost a full tank of premium instead of a full tank of regular. To be honest , most cars that require regular aren't appealing to me as I do have to drive alot and I like to enjoy my driving. I don't see how 4 octane points make that big of a difference especially when todays engines are more advanced than ever and have very sophisticated sensors that can make adjustments to the engine preventing knock / detonation. I can live with Use of a lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
 
I filled up from E (6 mile range left) on Monday with $40 of 91-octane, so you could use that as a point to make when talking to them.

Please read my post for the explanation of the knocking. It's not just a noise and it's not just decreased performance. There is much more to it, including bad gas mileage and ultimately engine damage.
 
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Thanks for all the info / advice peeps. I guess before I make a purchase i'm going to have to work this out with my employer. If I wait long enough maybe I can get a better deal on a SI :) , granted I can work something out with this new company. If not , my search for a fun to drive car will continue.
 
njhustler said:
You do make a good point Squiggy . I guess I can speak to my soon to be employer about this issue. Maybe I can have them set a fill up limit , say 50 bucks and maybe get almost a full tank of premium instead of a full tank of regular. To be honest , most cars that require regular aren't appealing to me as I do have to drive alot and I like to enjoy my driving. I don't see how 4 octane points make that big of a difference especially when todays engines are more advanced than ever and have very sophisticated sensors that can make adjustments to the engine preventing knock / detonation. I can live with Use of a lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
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You still need to take into account potential warranty issues.

Gas tank holds 13.2 gallons. Premium is genrally 30 cents more per gallon. That is about $4 per tank. Even if you go through two tanks a week, that is only $400 a year. If you were to get a vehicle with worse mileage, even 22 mpg, it would cost them considerably more. I wouldn't even discuss a fill limit. Just bring up the variance in fuel efficiency across vehicle types.

My first choice is an Si, but it requires premium gas and gets 28 mpg.
My ... choice is a WRX and it gets 19 mpg.
My ... choice is an F-150 and gets 15 mpg.
etc.

Let them chew on that.
 
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That's funny because the wrx sedan is my second choice. You bring up good points that will hopefully help me become a SI owner. Thanks.
 
Thesssfactor said:
I have been to around 10 gas stations on this list and I see the stations in which my cars perform the best were when running shell, mobil and maybe exxon gas.
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The 6.2L in my C6 would emit a bad sulfer smell while waiting at a traffic light. When I told the dealer, they said to use only top tier fuel. So I started using a nearby Exxon, and that got rid of the smell.

BTW, 93 octane only.

Amazing. :)
 
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KennyGS said:
I only run 93 in that engine.
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Just because of availability,right? I have a gas station I frequent that has 91 and 93 instead of like most stations here that only have 93.

edit: I think I misunderstood. I thought you were telling him to only use 93, when I see that you mean you only use 93.
 
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This is exactly why I would not want to pick up a si used. The fact that you're willing to roll the dice on a 22k car baffles me. If you do have engine issues, you're looking at like 6-7grand for a replacement engine. Go price it yourself.

njhustler said:
According to honda engineers that designed the j30a4 , using premium fuel gives it an extra 10hp and 10 ftlbs due to the computer adjusting for the higher octane.
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link to this story ^^ because I don't believe that for a second.

What Does That Number on the Pump Really Mean?
In the automotive world, there are many common myths, which are repeated so many times that, after a while, they eventually transform themselves into ‘facts.’ Unsurprisingly, many of these ‘facts’ have to do with gasoline, whether they be regarding fuel mileage, power possibilities or some other arcane aspect of the internal combustion engine. Gasoline can be a confusing topic, and it is easy to make assumptions about it that may seem logical, but which on closer examination, turn out not to be true. A perfect example of this practice can be seen with octane ratings.

What are octane ratings? Simply put, when you pull into the gas station and are presented with the array of different fuel grades that you can pump into your car, the numbers written above each button or nozzle indicate that particular grade’s octane rating. Typically, the range will run from 87 octane on up to 93 octane.

In the world of automobiles, it is tempting to associate higher numbers with higher quality. After all, more horsepower and more miles per gallon are a better thing, which feeds into our perception that more impressive octane ratings also equal higher performance. Gasoline companies understand this mentality and do nothing to dissuade drivers from it, labeling 87 octane gas ‘Regular,’ and 91 or 93 octane ‘Super’ in an attempt to reinforce this way of thinking. After all, since ‘Super’ is priced higher than ‘Regular,’ it’s in their best interest to convince as many people as they can that paying a bit extra means getting better quality gas.

Unfortunately, this is where the myth of what gasoline’s octane rating really means creeps into the picture. Time and again, people will be told that high octane fuel burns cleaner or more completely, and that it will give them extra power and better fuel mileage than Regular octane gasoline because it contains more ‘energy.’ These blanket statements are simply not true. In fact, the octane rating for gasoline has nothing to do with the amount of power locked inside of it – it actually relates to just how much a fuel can be compressed before igniting. The higher the number, the less likely it is to ignite under pressure.

Why would anyone want to produce a fuel that was actually harder to ignite once inside an engine? To understand the role that octane ratings and ignition pressures play in a motor, it helps to be familiar with the term ‘knock.’ Essentially, when gasoline is sprayed into a cylinder by a fuel injector and mixed with oxygen, engine designers expect it to remain there in vapor form until it is time for the sparkplug to light it up, causing the explosion that drives the piston down to generate horsepower. The timing of this explosion is critical, as gasoline that ignites too early causes ‘knock,’ which reduces engine output and efficiency and which, in worst-case scenarios, can actually physically damage an engine.

In most engines, knock is rarely an issue because the compression ratio – that is, the pressure that the air/fuel mixture is put under in the cylinder – is low enough that Regular gasoline’s octane rating is sufficient. There is absolutely no benefit to running Premium fuel in a standard motor, since it will never be able to take advantage of that gasoline’s higher knock resistance. However, more aggressive engine management schemes, especially those found in turbocharged or supercharged vehicles, can turn up the compression to a high level, requiring much higher octane gasoline to avoid knock.

How can you know whether your car actually requires Super gasoline or whether it can get by on Regular? Almost every vehicle will list the octane rating necessary to run it safely inside the owner’s manual. Some luxury or sportscars might even place a small reminder on the gas gauge itself stating ‘Premium Unleaded fuel only’ to make sure you don’t forget.

To wrap things up: no, you won’t see a power or fuel efficiency increase by running high octane fuel in an engine that has been tuned and designed for Regular gas, nor will doing so perform any extra ‘cleaning’ inside the motor. On the flip side, running low octane fuel in an engine built for Premium can increase the risk of engine damage and will certainly impact that unit’s overall performance. The next time someone tries to pass these myths off on you, you can try explaining to them how octane ratings really work – or you can just smile and nod, pay for your gas and move on.
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