What is the difference between 87, 89 and 93 gasoline at the pump?

Answer 1

The previous 2 answers are correct afa octance rating, but most don't know what octane is. Octane is one of the carbon chain molecules in the gasoline blend. More octane in a gasoline keeps the gas/air mixture from igniting at lower cylinder temperatures. In the newer higher compression engines, lower octane gasoline will "pre-ignite" causing knocking sounds, reducing power and eventually can burn a hole in the top of the piston. This is rare but in theory, it can happen. The gasoline/air mixture is taken into the cylinder during the intake stroke and is then compressed by the piston travelling upward during the compression stroke, the temperature inside the cylinder increases dramatically. If it reaches a temperature high enough to ignite the fuel BEFORE the spark plug fires, then you have pre-ignition, or ENGINE KNOCK and your engine cannot produce the power it is designed to produce. Soooooooo, the higher the octance is better- BUT- only in a high compression engine that needs it!! If you spend the extra money to put in 93 octane in an engine that doesn't have the compression ratio that needs it, then you've wasted your money and gained NO power. Actually, lower octance gas has a slightly higher BTU content (that means, it has more fuel to burn) than high octane gas. But it's the high octane gas that allows a high compression engine to produce more power!!!

Answer 2

Any car with electronic ignition should run on 87 without any issues. Every car manual I've seen says use premium fuel which makes you wonder. If the engine knocks the knock sensor will pick it up and the computer will retard the spark enough to eliminate the knocking. There might be a tiny amount of power loss but lets face it, at the price of premium fuel these days is it really worth it? Did you know most of the money gas stations make is on the premium fuel? That is where the most mark up is. I've never used anything above 87 and I've never had any problems.

Answer 3

OK it looks like you all ready got your lesson on octane now lets talk about your car
there have been independent tests on this if you want to look it up one was on get getharp Chanel 2 news Utah
older cars used different fuels for different compression ratios and carburation
new cars have fuel injection and knock and o2 sensors
they constantly adjust for all conditions so it doesn't really matter which you use you wont get better or worse with any one
the only problem is if you switch every tank one to the other the car will need to re learn what the settings need to be so if you switch ti high octane the first 50 miles you may get better mileage but Thain it will go back to normal your probably best to just put in what ever it cheapest and save the cash
unless you are driving an older car say pre 1983 like me i drive a 1971 car

Answer 4

this is the octane rating, which represents the engine knocking performance of a car.

engine knocking occurs during the power stroke, when the fuel in the piston chamber ignites due to compression instead of the spark plug. This causes the fuel's combustion timing to be slightly off, resulting in less than optimal power.

The number is really a representation of gasoline's engine knocking as compared to a mixture of two other chemicals- isooctane and n-heptane. Isooctane is given a rating of 100 (doesn't really knock) and n-heptane has a value of Zero (really knocks)

So, when you see a 93 octane rating, this means that this gas would knock like a mixture of 93% isooctane/7% n-heptane.

It is possible to have octane ratings above 100 since isooctane isn't the best anti-knocking substance, but I don't know much about them.

hope this helps explain it!

Answer 5

Octane levels in gasoline are different and the numbers on those pumps are different to expain the volume mixture in those. The volume mixture formula is listed under under the button if you look closely. The higher the number the hotter the fuel burns and you may get better miliege and compression which gives your vehicle more power in some cases.

Answer 6

They are octane ratings, 87 being the lowest and 93 being the highest or premium grade.Some engines will PING on the lower, that is pre-ignite.

Answer 7

See it all depends on the octane rating. The higher the octane rating the more flammable the fuel will be thus the fuel with more octane rating will produce more heat and ultimatly more efficiency.

Answer 8

Some good answers above. As far as some stating just use the cheapo stuff.....I disagree. I have a 5.7L HEMI and it KNOWS when 87 is used --- loss of power.

Answer 9

Octaine rating; some cars need a higher octaine to perform. See your owner's book or check on the filler cover

Answer 10

octane. different engines require different gasses get the one your car requires or you'll be changing fuel censer. about 50-150 dollars each