captain howdy

Your owners manual recommends 91. What does it say about running lower octane gas than your owners manual recommends? There are better additives in the higher octane gas, thats why your paying extra. I have never used cheap gas and I'm about to try just to save a few cents, especialy when it goes against the manufacturers recommendations.

monster5601

Lower octane will hold back the spark timing thus reducing the engine power.

Again, I ask you to validate your claims that higher octane fuels contain better additives.

It is not a few pennies, at least around SE Michigan, it is twenty or more cents per gallon for the higher octane.

When I state an opinion or an observation, I back it with factual data and references, please do the same. I'm willing to learn but I can't find any information supporting your claim.

BTW, I am a controls engineer at GM Powertrain, the octane recomendation is made so the customer never hears the knock. Because the fuel system contains an octane sensor, the PCM can almost always prevent knock at the cost of power output. Each octane level has a different spark table used by the engine control module.

captain howdy

Here you go: http://www.chevron.com/products/prod.../supreme.shtml
That is Chevron's reasoning why to use their premium gas with better additives . All gas suppliers use better additives in their premium gas. Like I said, that's why you pay more. Look at all of the major gas suppliers web sites and it is the same across the board. The better the gas the better the additives and cleaners which cause it to burn cleaner. Is that enough proof to back my claim? BTW 20 cents is a few pennies to me, I don't cheap out on anything in life.

monster5601

Nice marketing piece but, Chevron also claims it adds more than the required cleaning agents in all of it's grades, look here:
http://www.chevron.com/products/prod...dvantage.shtml

I took at look at Shell also just to compare the major brands. Shell adds the same cleaning agents to all of it's grades also, see here:
http://www.shell.com/home/Framework?...t_ga_1602.html

The Chevron piece made the assumtion your engine already has build up. The EPA has been requiring cleaning agents to prevent build up since 1995.

I think you are the victum of creative marketing.

captain howdy

Or you're a victim of false media. All I can say is thats what I have done my whole life under the recomendations of several people who I trust and know about vehicles. I'm going to change now or go against the manufacturers recommendations just to save myself pocket change. You and I will never see eye to eye on this so lets just drop it. I'll always believe there is a benefit to premium and you always believe differently. Nether of us is going to change the other ones opinion. No matter how many "facts" you present.

monster5601

You are right, I can't change your mind, all I can do is explore the data along with you.

It has been an interesting discovery of information and I've learned a few things I didn't know before so it was worth the investigation, thanks.

SoCalHHR

All marketing hype aside, I've run both regular and premium in my HHR (a 2.4L), and have noticed definite "seat-of-the-pants" performance and mileage gains using the good stuff.

That is the only reason I use it. (Well, that and it's only $2.00 more for a whole tank!)

GeeMac

I run 87 octane exclusively in my 2.4. When the weather gets warmer and I get more into 'cruisin' I will experiment with the higher octane. I am quite satisfied with the Interstate performance with 87 octane so far (about 42K)

captain howdy

Same here.

1BadPig

I got approximately 1 MPG (26 vs 25) better with the premium fuel with mix driving condition. At $0.20/gal more than regular, that's 8% more fuel cost (Regular = $2.40) using premium for a 4% increase in mileage. I'm sticking with regular. However, there is definitely a noticable seat-of-the-pant difference.