# 92 octane vs. 91 octane



## yesbill (Sep 23, 2004)

Would there be any substantial difference in engine performance using 92 octane vs. 91 octane? I live in San Diego, CA. and have yet to see a pump that offers 92. 04 phantom black,m6,three weeks new with 1300 miles.


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## LarryM (Aug 17, 2004)

Oh jeez! Didn't the dealer warn you about the 174.2 HP you'll be losing?

Well, as long as nobody imports 92 octane from Nevada, at least you'll be on the same relative standing as everyone else.  

---Larry


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## yipching (Oct 5, 2004)

*This may be a dumb question, but here goes...*

Why do different states have varying octane ratings of their premium fuels? Is it a state law thing? 

I live in upstate NY, and our high-grade gasoline is 93 octane, sith some Sunocos offering 94...


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## TORRIDONE (Sep 14, 2004)

You will never find 92 octane in California it is not available period, but if you could it would good to use it as the computer system on your car would be less likely to Knock retart your car resulting in better performance!

Robert


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## LarryM (Aug 17, 2004)

yipching said:


> Why do different states have varying octane ratings of their premium fuels? Is it a state law thing?
> 
> I live in upstate NY, and our high-grade gasoline is 93 octane, sith some Sunocos offering 94...


Because they can.  

"Normal" Premium here is 93 octane as well, but a handfull of stations have "Racing" fuel that is 100 octane. It was $4/gallon when I last looked.

---Larry


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## blue goat (Aug 19, 2004)

The higher the altitude the lower the octane. In Amarillo, Tx. where I'm at the highest you can buy is 90. I understand that in the mountains premium is 87. The closer to sea level the higher the octane allowed. Barometric pressure or something I don't understand. Explained to me by a gas distributer in the area when I went looking for 93.


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## GlennH (Sep 22, 2004)

91 is the normal premium here in KC. Occassionally I find a BP station with 92. I drove fifteen miles down the freeway last Saturday to a Phillips 66 Truck Stop and put 10 gallons of 100 octane @ $3.99 per gallon. Just wanted to see what it did. I think it's a little faster but don't really know for sure. It doesn't start up as fast as with the 92 but it looks like it's getting a little better gas mileage and, needless to say, I have my foot to the floor as often as possible. I saw a review of gasolines on the web somewhere and they tested 87 using octane additives and then 102 (or somewhere in there) and there was a world of difference in the hp. The higher octane fuel gained 5 to 10 hp more than the 87 with the additive and they were able to manually advance the timing a lot further with the 102. The point was that the higher octane fuel was just an all around better gasoline.


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## TORRIDONE (Sep 14, 2004)

I think people are mis understanding what octane means to you! If you have a high compression engine higher octane is benificial to a certain point. In an old 60's high compression car with no computer management if you could not get the proper octain gas your car would knock or pre ignite the fuel in the cylinder before the spark plug ignited it very bad, but you could manually retard the timing advance to reduce or eliminate the problem! and also reduce performance, move forward to the gto it has an electronic system in place to compensate for lower than optimum octane and retards timing so your car runs without knocking but at a lower performance level. The trick is to buy the octane level that will allow your GTO to run with no knock retard thus obtaining maximum performance! IMO 91 octane in california is slightly to low to allow full performance the car runs but not to its true potential! on the other hand 100 octane is more than likley to much and does nothing more than 93/94 octane other than cost more! You are not being nice to your car by buying higher octane than your car requires! As the octane number increases all it means is that you can squeeze the air fuel mixture tighter before it pre ignites and damages the engine. years ago the oil companies used to only put the good additives into their premium gasolines! since the early 70' federal law has mandated these additives in all fuel grades.

Robert


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## GlennH (Sep 22, 2004)

Thanks for the info. Even though I hadn't intended to fill up every week with 100 octane fuel, I won't do it again as I definitely don't want to hurt my engine. 92 octane is the best I can find here in KC so that will just have to do. As I had mentioned, I wasn't really sure I could tell any difference in the performance with the 100 octane anyway. With your explanation, I now know I more than likely wasn't. In the reference article I read about the octane additive, they kept advancing and retarding the timing when they changed the fuel so they were probably experimenting on an older muscle car without all the computers.


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## Tuxedo Mask (Sep 13, 2004)

So what will happen if you use 87 octane in the GTO?? Gas over here in Vegas is very expensive. $2.30 for premium. Does using 87 octane with additive good for the engine?


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## Neo-GTO (Sep 29, 2004)

Tuxedo Mask said:


> So what will happen if you use 87 octane in the GTO?? Gas over here in Vegas is very expensive. $2.30 for premium. Does using 87 octane with additive good for the engine?


If you put in 87 Octane, just make sure the engine is not knocking. There will be a slight degredation in performance from the lower octane as the computer will have to retard timing a little to compensate. However, it should retard the timing and there should not be any knocking. BUT, if it does knock, you definately will want to go to a higher grade.

I see no real problem with using 87 and an additive, but is it really that much cheaper than buying the higher grade right at the station? (serious question, I have no idea how much those octane booster additives cost).


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## Tuxedo Mask (Sep 13, 2004)

Neo-GTO said:


> If you put in 87 Octane, just make sure the engine is not knocking. There will be a slight degredation in performance from the lower octane as the computer will have to retard timing a little to compensate. However, it should retard the timing and there should not be any knocking. BUT, if it does knock, you definately will want to go to a higher grade.
> 
> I see no real problem with using 87 and an additive, but is it really that much cheaper than buying the higher grade right at the station? (serious question, I have no idea how much those octane booster additives cost).


I am not too sure how much the additive cost. I am just asking because it seems here in Vegas that gas prices are rising almost at an hourly rate. Regular unleaded is at 2.20!!!!! i put in about 15 bucks yesterday and it only filled up about 1/4 tank. So if i put in 87 for the time being i will be okay?


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## Neo-GTO (Sep 29, 2004)

Tuxedo Mask said:


> I am not too sure how much the additive cost. I am just asking because it seems here in Vegas that gas prices are rising almost at an hourly rate. Regular unleaded is at 2.20!!!!! i put in about 15 bucks yesterday and it only filled up about 1/4 tank. So if i put in 87 for the time being i will be okay?


Your engine should run ok on 87 Octane, but pay close attention to it and make sure it doesn't begin to knock. If it doesn't knock, you are ok. If it begins to knock, get octane booster and dump it in. It shouldn't knock because the engine should be able to compensate.


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## TORRIDONE (Sep 14, 2004)

*87 octane*

If you decide to try 87 octane drive up a slight incline with light throttle and listen carefully for knocking or pinging! The price you may pay is melted or a hole in your pistons! In my corvette (same engine as GTO Ls1) my ex wife put in a few gallons of regular 87 in an empty tank, when she got home told me the car was running awful and shaking alot! Sure enough it was running poorly drove to the gas station and filled her up with premium helped smooth out the idle quite a bit but still not normal, car has only seen premium since! Oh seemes to me here in Ca premium has gone up .25 in the last ten days 2.45 to 2.50 a gallon  

If you go to the corvette forum and do a search there is lots of information on octane,octane boosters ect.


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## Tuxedo Mask (Sep 13, 2004)

Well, looks like it's gonna have to be peanut butter and jelly sandwiches from now. i didnt realize that using premium is a must with this car. i am going to give this car a couple of months...if it takes too much money from me.....i will trade in the car.


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## TORRIDONE (Sep 14, 2004)

*Don't do it!!!!!!!!!!*



Tuxedo Mask said:


> Well, looks like it's gonna have to be peanut butter and jelly sandwiches from now. i didnt realize that using premium is a must with this car. i am going to give this car a couple of months...if it takes too much money from me.....i will trade in the car.


Look premium is about .20 a gallon more if you were to buy 1,000 gallons of gas a year good for at worst 15,000 miles or 21,000 miles if you drive thrifty by coasting to red lights ect it will cost you $200.00 extra a year about $17 a month extra. My fiancee gets about 18 mi /gal in her 6 speed avg, I think she can do better if she would up shift to 5th faster. my vette averages 20-21 mpg overall, at 80 mph on a 600 mile round trip to vegas I get 29.8 mpg.

Also think about the trade in hit you would take! Keep the car enjoy! Don't do it.

Robert


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## Tuxedo Mask (Sep 13, 2004)

TORRIDONE said:


> Look premium is about .20 a gallon more if you were to buy 1,000 gallons of gas a year good for at worst 15,000 miles or 21,000 miles if you drive thrifty by coasting to red lights ect it will cost you $200.00 extra a year about $17 a month extra. My fiancee gets about 18 mi /gal in her 6 speed avg, I think she can do better if she would up shift to 5th faster. my vette averages 20-21 mpg overall, at 80 mph on a 600 mile round trip to vegas I get 29.8 mpg.
> 
> Also think about the trade in hit you would take! Keep the car enjoy! Don't do it.
> 
> Robert


Oh trust me, i love the car. Right from starting the ignition, you can tell the car has some power. But right now, i guess it depends on the freakin price of oil per barrel. Gas is going way high and it seems like no end in sight. i was thinking of trading it in for a G6....ONLY IF I HAD TO!


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## NJG8GT (Nov 14, 2007)

Tuxedo Mask said:


> So what will happen if you use 87 octane in the GTO?? Gas over here in Vegas is very expensive. $2.30 for premium. Does using 87 octane with additive good for the engine?


Wow, $2.39 for premium gasoline in 2004!!! I wish. 93 Sunoco Octane is costing me over $3. Some interesting old posts.


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## ls7gto (Feb 2, 2008)

Tuxedo Mask said:


> So what will happen if you use 87 octane in the GTO?? Gas over here in Vegas is very expensive. $2.30 for premium. Does using 87 octane with additive good for the engine?


2.30!?, we have 3.16 over in jersey


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## koman (Sep 25, 2006)

3 bux even in the chuck.


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## NJG8GT (Nov 14, 2007)

ls7gto said:


> 2.30!?, we have 3.16 over in jersey


That was in 2004! I was just showin' what they were talking about back then.


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## fergyflyer (Apr 18, 2005)

NJgoat said:


> That was in 2004! I was just showin' what they were talking about back then.


Kinda funny that they were upset over 2.30 per gallon, and that was a high price for Caifornia fuel. 

I can find regular for the Cav for 2.85 around here and the premium the Vette drinks is 3.09-3.19.


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## Tacmedic (Feb 24, 2006)

Tuxedo Mask said:


> i didnt realize that using premium is a must with this car.


You didn't see the big sticker on the fuel filler door? Big red letters, "Premium Fuel Recommended" :lol:

Just messing with you


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## LOWET (Oct 21, 2007)

yesbill said:


> Would there be any substantial difference in engine performance using 92 octane vs. 91 octane? I live in San Diego, CA. and have yet to see a pump that offers 92. 04 phantom black,m6,three weeks new with 1300 miles.


REMEMBER, that all octane ratings at the pumps are plus or minus 2-3 percent, you coudd be paying for 93 and you might be getting 89-91. My cousin used to work for a Company that went from gas station to gas station testing fuel octane. Most of the times the advertized rate was on the low side but within the legal 2-3 percent.


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## LOWET (Oct 21, 2007)

fergyflyer said:


> Kinda funny that they were upset over 2.30 per gallon, and that was a high price for Caifornia fuel.
> 
> I can find regular for the Cav for 2.85 around here and the premium the Vette drinks is 3.09-3.19.


91 to 93 octane in Connecticut is about 3.45 PG


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## NJG8GT (Nov 14, 2007)

LOWET said:


> If you use a fuel additive, ALWAYS use the same Brand Name and use it at every fill up. If you only use it once it a while it messes with the cars computer system and will contantly be adjusting for the change in Octane and chemicals and could mess up a good tune. I run straight 93 Octane all the time but I do add a little Fuel stabilizer and a drop of marvel Mistery oil in the winter months when the car is rarely driven



On a post late this past year, on a fuel additive poll, I believe I asked who used fuel additives and what brand. I listed Marvels Mystery Oil and No one said they used it. I thought u just posted fuel stabilizer and a good fuel cleaner once a year:confused I have used the Mystery oil for along time, boat, motorcycle, and my cars. I think I even added some to my rider mower!


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## silversport (Mar 23, 2007)

the computer is made to re-evaluate constantly...it takes into account variables like octane, additives, etcetera...I wouldn't worry too much about the coimputer having to do its job...
Bill


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## LOWET (Oct 21, 2007)

NJgoat said:


> On a post late this past year, on a fuel additive poll, I believe I asked who used fuel additives and what brand. I listed Marvels Mystery Oil and No one said they used it. I thought u just posted fuel stabilizer and a good fuel cleaner once a year:confused I have used the Mystery oil for along time, boat, motorcycle, and my cars. I think I even added some to my rider mower!


I do you Marvel Mistory oil. but I use such a small amount that I didn't even mention it. It does work as a good upper cylinder lube. I might use a quart a year


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## fergyflyer (Apr 18, 2005)

Another thing that Marvel Mystery Oil does is lubricate the fuel pump and injectors. With todays fuel's using more alcohol, it's become more important to lubricate the fuel system as well as the upper cylinder area. Marvel is good. Another is Lucas Fuel Injector Cleaner and Upper Cylinder Lubricant.


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## LOWET (Oct 21, 2007)

fergyflyer said:


> Another thing that Marvel Mystery Oil does is lubricate the fuel pump and injectors. With todays fuel's using more alcohol, it's become more important to lubricate the fuel system as well as the upper cylinder area. Marvel is good. Another is Lucas Fuel Injector Cleaner and Upper Cylinder Lubricant.



:agree


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