Why does it burn cleaner? Higher octane fuel burns slower, wouldn't that give you a less complete burn? Also, all grades are required to have the same detergants / cleaners so regardless of octane they should have the same "cleaning" performance. That is what Shell is advertising. From the last head I took apart @ 52k, the valves had significant deposit, though from the looks of it the deposits were caused by the valve oil seal leaking and the oil baking off on the back side of the valve, not from fuel deposits.

I'd love to get a site listing ethanol per station though, it had a big impact on my trip last weekend. I got 32 MPG driving on the shell fill-up, and only 28 from the Pilot station with "up to" 10% ethanol. The entire drive was on I-95, flat @ 80 MPH and similar, 40's and rainy conditions. This was two fill-ups one way so I was driving the same direction the whole time.

 

Okay i have read all the links and have done additional research. I have been using Premium gasoline since i bought my tc two years ago...not anymore!!!

your octane rating for your vehicle depends on the compression ratio of your engine.
Higher Compression=Higher Octane
there are other factors like climate and altitude but for the most part compression. it is recommended you use the lowest octane rating possible without causing engine knocking.
now as far as the cleaning agents part goes. all gasoline grades are NOT required to have the same amount of cleaning agents. Shell does have the new Nitrogen enriched fuels on all three grades which equals to twice the cleaning agents required by law. now the premium grade has the highest concentration which i believe is five times the amount required by law. but even all this cleaning agents isnt required unless you have lots of engine build up.

 

The manual says the minimum octane rating our cars can handle is 87. It doesn't recommend that we run 87 only. I don't know why this is a sticky. Like someone has said already, there is no hard evidence to prove either side's argument. But if I was going to a track event I definitely wouldn't put 87 octane gas in my car.

 

wtf. should i use 87 or 93? ive been using 93 since i bought my car. i remember putting 87 couple times and my motor would shake a lil

 

Are you serious? Did you read ANY of the links I posted? Especially the CarandDriver one that was the first link (it's a tinyurl.com one b/c the link is long). THERE IS EVIDENCE.

If you run anything other than 87 in your NA tC, you are simply wasting your money. There is no other way to say it.

 

o well....93 does not hurt my motor from my tc experience....so ill just keep wasting money i guess.... i was using 93 on a corolla 95....lol

 

No, it won't hurt anything... it's just no helping anything either.

On a 95 Corolla, it might actually help. Many of the articles point out that it can more helpful with an older car and an older engine. With a car that is less than 5 yrs old (any tC), there's no way you're going to get that "old engine benefit."

You would be better off just making sure you are using one of the "top tier" gas suppliers: toptiergas.com.

 

when i put 93 on my tc makes me feel like im given her a good meal
about the corolla i believe you. your rite! couple mechanics have told me the same

 

who cares about wasting money. the difference adds up to about $100 a year. big deal. you should use the lower octane becuase its less dense.
the compression on the tc is too low(speaking N/A) to burn all the gas. the more gas you burn the cleaner and more powerful output your'll recieve.
thats why you should use the lower octane.

 

I can only speak from my own experience here, and I hope it wasn't my mind playing tricks on me. I ran my tc almost empty and put 4 gallons of 100 octane fuel in the tank and went to the track. My times were horrible because i bent an Ingals Stiffy and broke two motor mounts out there. However, prior to the track, I spent 20 miles running it hard to try and get the ECU to retard timing. I "felt" a difference. The car pulled harder through 2nd and 3rd gear. In addition to this, I could let the clutch out, idle along in a parking lot and just punch it, and when I hit 3600 RPM it would haze the tires. It wouldn't do that before I had the 100 octance gas in there (same night, same temp, same parking lot).

Also, in addition to this, my friend with an 07 Civic Si (yes, I know it has a high compression ratio) did a dyno run with his car. He ran 3 runs with 91 octance, and then 3 runs with 100 octane and he made 5 more horsepower. I have seen the dyno sheets.

Edit: I run 87 around town.

 

I Don't remember where i read it but lower octane pump gas actually has more energy than higher octane. this is because to get higher octane fuels they have to blend aromatic fuels (toluene is one, yes its paint thinner), the only drawback is aromatic fuels have a lowe btu rating tha just straight gasoline, so you will actually get better mileage from 87 octane fuel if you engine can run it. add boost and its a different story

 

Okay...don't hate...lol.... here's my 2 cents.... The ONLY reason I run premium in my tC.....is because of where I live...in the winter months....providers like Shell...are among the few that if you run premium (91 octane here) they do NOT dilute it with ethanol like the lower grades are... and I am literally getting 70-80 miles more out of every tank because of it...so Im willing to fork over the extra buck or two b/c it more than pays for itself

 

This makes sense. Saying premium is better because "I think my car tuns better," is not.

And 91 isn't premium . I don't know what I'd do if 93 wasn't available, I don't think my car would survive on 91.

And they do the same for gas in Arizona. I was getting 19-22 mpg city / 26-28 hwy on my old tC when they mixed ethanol for the winter months. I have no idea if thy diluted 89,91, or 93 octane.

 

 

I think it's silly that we have a sticky dedicated to saving people about $100 a year, but no sticky in the forced induction forum telling people how they MUST not go lower than 91 octane. I guess saving people a few bucks is more important than saving people thousands of dollars in engine repairs.

 

Hey there bro.... debating what is "premium" depends a lot on what part of the country you live in... I've actually spent several years in Phoenix, AZ...but live in CO now... Basically 91-93 is fairly standard for "premium" blends... I had mentioned that Shell Gasoline company does NOT put any of that ethenal crap in the their premium blends....i.e. 91+ octanes... and I have noticed literally a 70-80 miles extra in every tank during the winter months here.....plus Shell puts aditives in their premium fuels that really burn much more cleaner than their competition.

 

and there it is. the best post on this friggin topic lol. and how about a topic "GET A TUNE IDIOT"

 

Sorry, but if you don't know that you need to run premium, you shouldn't be boosting a car. And if you ignore everyone about that, you deserved the blown motor.

 

so you think this topic would be more useful?

 

That's exactly what I was thinking.

And this thread isn't necessarily about saving a few $. It's more or less about education and getting people to see that they don't need to be using a higher grade fuel than is called for. As you can tell, there are a lot of people who use a higher grade because they really think it is better (when it is not).

Like Carbon said, if someone is going for boost and hasn't done enough research (or doesn't have enough common sense) to know they need a higher grade of fuel, well, they shouldn't be boosting at all.