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Super Octane Gas

I have a 2000 Saturn 4 cyl wagon and accidently grabbed the wrong nozzle and pumped about 6 gallons of 100 + octane supergas into my half full gas tank before realizing my error… What will this do to my engine?

It’ll do nothing at all.

Octane rating is just the measure of the fuel’s resistance to flash from heat of compression. There is no more power or anything detrimental to your engine in it. All you’ve done is pay for octane your engine will not have the capacity to need.

On the other hand, should you modify your Saturn engine to NASCAR tune in the next few miles, you’ve got the gas to run in it.

Thanks for the reply … I’ll just have to look at it as an extremely expensive fill up … Aargh !!

One tank will not hurt it. I would not make a habit of it as it certainly will cost more and you will not gain any advantage and some cars can even be damaged by continued use.

Nothing, the octane requirement on your fuel door is a minimum needed.

That works out to about 95 octane. As the rest said, don’t sweat it. Putting low octane fuel in a car that requires high octane fuel could be a problem, but your mistake will only cost you about $0.40 per gallon.

Thanks everybody…

“extremely expensive”? 1 or 2 dollars difference?

Nothing really; it will run just as well; you just wasted some money. If it had been regular gas in a premium engine car, you would be advised to top it up with super to avoid possible pinging.

I would not drive this car . wait untill summer and tow it to a NHRA strip. you might bet john forse

I’m kinda curious how 110 octane would be handled in a car that calls for 91, like a WRX STi

I’m not quite sure what 110 octane is or if you just threw that out as a figure… We have a 100 octane pump at the racetrack so we don’t have to bring our own fuel, but I’ve never seen 110. The misunderstanding a lot of people have is that super unleaded is ‘SUPER’ gas. It’s not. You’re paying more for less. The higher the number, the less combustible it is. The higher your compression (turbos excluded), the less flamible fuel you have to have to prevent pre-ignition, which is the pinging you here if too low of octane is used. I can’t remember the specs, but diesel and super duper JP8 jet fuel are like 120 to 140 octane. VERY UNFLAMABLE! So too low octane causing pinging from pre-detenation. Too high octane, and your engine just can’t ignite it, and make use of the fuel if you don’t have the compression. Of course I said turbos excluded because, turbos on average have below average natural compression, but the turbo pressure raises that dramitacally. So a stock STI would have no benefit from SUPER DUPER high octane fuel, unless you cranked up the turbo boost to astronomical pressures to raise the compression dramatically.

Station where I get my gas has a lone pump for 110 octane racing fuel. It was shut off when I got my gas today, so I dunno how much per gallon it is, but last I looked it was atleast $1 more per gallon than 93(87, 89, 93 octane is normal here in Ohio). I figured it’d be akin to putting 93 octane in a car that calls for 87

Man I’m coming up there with a 200 gallon tank to fill up!! It costs us $5 a gallon at the track! On the plus side I don’t have to transport it.

The 110 octane you refer to exists, but usually only at airport aviation fuelling stations. It is also a racing fuel, not normally sold through gas pumps.

Diesel and jet fuel, which is mostly kerosene, have octane ratings close to or even less than zero. Mix diesel with your gas and your engine will ping.
High ignition point and high flash point are two different properties. Motor oil has a very high flash point, the temperature at which there are enough vapors in the air to ignite, but it has a low ignition temperature. Spilling motor oil on a red hot header can start an oil fire. It takes more than a red hot surface to set gasoline fumes on fire.

Well, as I said, it was a while ago that I seen the price and it was like $4.35/gallon, this was last year I took a glance at it. The guy says he prices it according to the market, not the way he does the normal gasoline pricing.

Thanks for the correction. I thought that was the Cetane rating, since they don’t really have an octane rating for diesel. I was under the impression that if diesel ‘had’ an octane rating equivelant, it was like 140.

Yes, cetane rating is kind of opposite of octane rating. Spark ignition engines that burn a homogeneous air fuel mixture knock when a part of the mixture ignites too soon. In diesel engines, knock happens when ignition is delayed. You want the fuel to be burning as soon as it sprays into the cylinder. If a bunch of it accumulates before igniting, it goes off with a bang.

Mix high cetane rating diesel with gasoline and you lower its octane rating and your gasoline engine pings.

Mix high octane rating gas with diesel and the cetane rating is lowered and your diesel engine knocks. Mix a lot of gasoline with your diesel and you need a tow truck.