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California used to have 92 octane. There was a big debate between 76, who owned the formula for making 92 octane, and everyone else. No one wanted to pay 76 to make 92 octane so they started making 91.

As for the higher octane gas... California uses more premium gas than any other state so they can't make enough higher octane gas to satisfy demand.

Here is something Sport Compact Car magazine's Technobabble wrote back in 2001.

By the time you read this, residents of Nevada and Arizona will have been screwed too. What, you don't live there? Just wait, you're next.
It's not like West Coasters haven't been screwed before. From roadside smog dynos to tickets for shiny mufflers, we're used to the man getting us down, but this time they're hitting us where we eat. This time they're taking our gas. We already have pretty crappy premium fuel in California. Just like most of the West Coast, we're stuck with 92 octane, while much of the Midwest and the East Coast got to play with 93 or better. Now, as of August 1, 2001, the best we can get is 91. Time to turn down the boost.

On the off chance you're only now trading in your Schwinn 10-speed on a twin-turbo Supra, I guess I should stop here and explain what octane is and how it affects your engine.

When fuel is injected into the cylinder, compressed and ignited, one of two things can happen. It either burns quickly and smoothly, shoving the piston down with a strong, even push, or it explodes all at once, releasing its energy in a sudden burst of heat and pressure. This explosion is called knocking or pinging, and it's something engineers like to call "really bad."

Knock is usually ill timed, occurring early in the combustion cycle when the crank and rod are still straight up or even worse, still trying to complete the compression stroke. As a result, all the energy released slams into the top of the piston without actually turning the crank. When this happens under stressful enough conditions--like, 20-psi of boost in a Miata--you start breaking things. Usually the ring lands; however, if your pistons are strong enough, you might get lucky and blow a head gasket.

Octane, for those of you still on the bike, is the rating of a fuel's ability to not do this. The higher the number, the less likely the fuel is to detonate. What this means to us, of course, is the higher the number, the more boost we can throw at that Miata. High-octane gas isn't just for tuners though. Plenty of stock cars depend on the stuff, including a Celica GT-S with its 11.5:1 compression, or a turbocharged WRX or Volkswagen 1.8T.

These cars rely on high-octane gas to keep from detonating. Feed them 91 octane and they won't start breaking things, because their knock sensors will see it coming and retard the timing, turn down the boost or otherwise reduce your chances of having any fun.

Whose fault is it this time, CARB? The EPA? The CHP? None of the above. This time we're being victimized partly by the oil companies, and partly--this is the one that hurts--by ourselves.

You see, when crude oil is refined into gasoline, the refinery doesn't have all that much control over what comes out. Crude oil is full of all kinds of stuff, and a refinery simply separates it, sorting all the iso-this and hepta-that in order of density. The really heavy stuff, like tar, is near the bottom, while the really light stuff, like butane, is near the top.

Somewhere in the upper ranges of the stack are the components of gasoline. There are between 10 and 15 different blend stocks, each with a different octane rating, which are mixed together to make gasoline.

The crude oil being used and little else determine the amount of each blend stock available for mixing. Generally, if you just dump all the blend stocks into a bucket, you end up with something around 88 or 89 octane. If you're selective and only mix the good stuff, you can make 92, 93 or even 95 octane. But once you take out the good stuff, you're left with crap--something like 85 octane. Then you have to leave enough good stuff in the bucket to bring this pee-water up to at least 87 octane. This limits the amount of 95-octane gas you can make. If you make 93-octane premium instead, you use up less of the high-octane stocks, allowing you to make a higher proportion of premium fuel.

In the Midwest, where an extensive customer base of good old boys in pickup trucks consume vast quantities of 87 octane, demand for premium fuel is low enough to make genuine high-octane premium.

In California, however, Lexus-driving executives suck down premium fuel like it's Evian, so 92 was the rule.

CARB isn't entirely innocent. Many of its standards for evaporative emissions and misdirected attempts at oxygenation have raised the manufacturing cost of high-octane gas, but it doesn't seem to be behind the sudden change to 91. Instead, according my super-secret oil industry mole, it all comes back to money. Unocal, you see, has a patent on the 173 easiest ways to make California-friendly 92-octane gas. As a result, every other oil company has to pay Unocal 5.75 cents for every gallon they make using one of these techniques. They haven't actually been paying it, but that's an issue for the lawyers to sort out.

Suddenly it's pretty obvious why our gas sucks, but why doesn't Unocal still sell us 92? Because it can't. In 1997, Unocal sold off all its 76 gas stations, and with them, its ability to decide what kind of gas to make. All Unocal can do now islook for oil, suck it out of the ground, and wish it had some way to make everybody else keep using its patents. You see, not only did Unocal screw us, they screwed themselves.

Ironically, the only gas stations in California with anything better than 91 octane are the ones Unocal used to own--the few 76 stations offering 100-octane race fuel. You can locate these elusive stations at www.76.com, but bring your wallet. The current going rate is $6.00 a gallon.