Regular unleaded 87 vs mid grade 89 vs premium??

[tkenway]

I'm fully prepared to pull my foot out of my mouth after I ask this, since I may well be in the wrong board. Hope not. (I hopw it's not a DUH answer, either? I'll feel like a dummy.)

I went to the gas station a few days ago and, being the oversightful genius I am, hit the wrong button with my (removed) when I went to squeeze back to the nozzle. (I parked too close. Again.) I filled my Vibe with 89 mid grade fuel. I'm due for a fill up again at the end of the week, and I haven't noticed any issues, but I might be wrong. I usually put regular in my tank, but I've gone through a half tank of 89 octane. The biggest difference I feel and observe is the responsiveness of the vehicle, with the revs maintaining a lower level by a little bit (no more than 100-200 rpm). I've also noticed that the car seems to up its revs when I come off the line from a stop, like in a drag race, higher than usual.

The question I have is, is putting 89 in my car bad for it, or should I just use the 87? Did I do a bad thing?

[Doug14]

Well i assume you dont have a gt because that requires 91 or higher. Also assuming you dont have an 09/10 vibe (as i own an 06) you havent done any damage. Ill run a tank of 89 or higher once and a while to kinda clean it out, never any issues. Just dont put diesel in it haha.

[Salsa Guy]

No putting 89 in a car that only needs 87 is fine. You may even find your car has some extra "legs". Putting 87 in a boosted car or GT can spell trouble.

[Vulcan05]

The higher the octane the SLOWER it burns. Any power gain is strictly imaginary.

[tkenway]

Thanks, guys! I run an 06 Base, no mods yet.

Glad I haven't done any damage.

[Chiadog]

I run mid-grade 89 octane nearly exclusively in my 05 base without any issues. I run mid-grade only to get fuel that is ethanol free. When I am forced to buy 87 octane 10% ethanol, I notice an average drop of 1.0 mpg. usually 32mpg > 31mpg.

[beemerphile1]

The higher the octane the SLOWER it burns. Any power gain is strictly imaginary.

Absolutely, the only damage is to the wallet because they paid more than necessary. Any improvements are imagined.

[Rayven01]

I run mid-grade only to get fuel that is ethanol free.

I wish I could do that in St Louis. Unfortunately mid-grade here is just a blend of premium and regular, and premium is just too pricey to justify the small MPG bump.

[vibenvy]

Our 2009 Vibe GTs always get gas from the same local Citgo station. Up until March of 2012, their regular was 89 octane, mid grade was 90.5 octane and premium was 92 octane. It is now 87 octane regular, 89 octane mid-grade and 93 octane premium. I never noticed any difference with the 89 octane and have not noticed any difference since they switched to 87 octane. So, as others have said, no you didn't do any damage to your Vibe and as long as you have a non-1st gen GT Vibe, there is no need and no benefit to using anything over 87 octane regular.

[tkenway]

Great, thanks so much for the input, guys. I'll keep using the 89, just because I do dislike running 10% ethanol through my cars. My Camry had better check up using 89 instead of 87. My mechanic mentioned something about ethanol being more harmful to engines and seals over a long period of time, is he right?

[beemerphile1]

...My mechanic mentioned something about ethanol being more harmful to engines and seals over a long period of time, is he right?

Yes, he is right. Unfortunately things will be getting worse. What has been forced on the public so far is 10% ethanol (E10). It was recently agreed to start forcing E15 (15%) on the American public. Expect your lawnmower, snow blower, chain saw and ALL motorcycles to have related failures. No motorcycle or small gasoline engine is okayed by the manufacturer to run E15.

[Doug14]

Also forgive me if i sound dumb, but i never really looked into why they're putting ethanol into gasoline. Is it just to "water it down"? Or is there some benefit to it ?

[Rayven01]

To reduce dependence on foreign oil (corn ethanol is produced in the US). Unfortunately other than the fact that it is US made, basically every other thing about it is bad (costs more, uses more energy to produce, gets worse MPG, is bad for engines not designed for it, drives up corn prices artificially, etc etc).

[Doug14]

Oh well that makes sense...lol thanks for the info!

[Vulcan05]

Here's some food for thought.

Charles Grassley is a senator from Iowa. He is on the farm committee. Chuck, his son Robin and grandson Pat (who is in the Iowa legislature....see a pattern developing here?) own farmland. Between the three of them, they have taken over ONE MILLION TAX DOLLARS from the farm subsidy program in the last 15 years, Now, Chuck is an "ultra conservative". Unless he can get his paws in the public feeding trough.

Guess how he voted on 15 percent ethanol?

[circuitsmith]

The higher the octane the SLOWER it burns.

Not true. Octane only affects the resistance to spark knock. Look it up.

Any power gain is strictly imaginary.

Quite true.

Also, one advantage of ethanol is its effect of boosting octane.
Pure ethanol is 140 octane. Useful in race cars.
I agree however it's a bad idea to make it from corn for the general public.

[Vulcan05]

Click on this link, go down a couple of paragraphs to "Octane Facts".

It says"High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high."


http://mn.gov/commerce/weights-and-meas ... eFacts.pdf" onclick="window.open(this.href);return false;

[circuitsmith]

That document is mistaken, but close enough for a non-technical "consumer guide".
If high octane fuel actually burned slower the engine would need more spark timing advance, or there would be power loss.

The Wikipedia entry has more technical detail and makes no mention of high octane fuel "burning slower":

http://en.wikipedia.org/wiki/Octane_rating" onclick="window.open(this.href);return false;

Here are explanations that octane and burn rate are not related:

http://motorcycleriderz.motionsforum.co ... fuel-burns" onclick="window.open(this.href);return false;

http://www.2strokeheads.com/tech-octane-detonation.htm" onclick="window.open(this.href);return false;

[triz]

Actually running 93 every once in a while will help keep your fuel system clean. Drop some Techron or Amsoils PI Performance Improver every so often to keep the fuel system clean. Also clean your MAF and throttle body every so often will also keep your performance on your vehicle running top notch.

[Th17kit]

Vulcan this is getting edgy for the regular forum but I like where you're going with this.

[tkenway]

I love it when politics accidentally happen on my posts.

Thanks for all the useful info, guys! How do we stop the E15? I like my car functional.

[jake75]

Don't be so sure that the 89 octane does not have up to 10% ethanol. In many states, and I think that includes Ohio, labeling alcohol content in gasoline is not mandatory.
Actually I don't think they ought to be able to call a 90/10 gasoline/ethanol blend "gasoline".
You can't call a 90/10 blend of maple syrup/sugar syrup "maple syrup". Or a 90/10 blend of butter and vegetable oil "butter".
A google search will tell you what states permit this non-disclosure.