Why is premium gas recommened for the 2007 Mitsubishi Endevor?

Answer 1

Premium gas burns slower than regular unleaded and is required in many modern high compression engines to prevent pre-ignition or "pinging." When you attempt to use regular gas in a high compression engine, the mixture burns completely before the pistons reach TDC (top dead center) which is what causes this problem.

If premium gas is not available you can alleviate the problem by retarding the ignition timing slightly, but that will prevent the engine from achieving maximum performance and will alter the emmissions.

Answer 2

Generally, automobile manufacturers that recommend premium fuel in certain models do so because the engine runs smoother or gets better mileage with that fuel. (I work in a full-service gas station, so I see a lot of these stickers on the inside of fuel doors). I've filled up a few of these Endeavors, but most of the people said regular works fine. Only one said to use premium.

The higher octane of the fuel means that the fuel is more refined, and therefore burns better. In some vehicles, this yields smoother performance and better gas mileage. In others, it can have a negative effect. Generally, luxury and performance cars only have problems with regular fuel, and even some of them don't (I know people who put regular in BMWs and Chevrolet Corvettes and they run fine; I tried putting premium in my Geo Tracker once, and the gas mileage went down a couple miles per gallon).

If you've already bought the Endeavor, there is one thing you could try to see if premium fuel is absolutely necessary. The next time you fill up, just use regular.

If the engine starts to knock, make excessive noise, or you notice a substantial drop in gas mileage or performance, stop at a gas station or Wal Mart/Meijer/KMart/etc. and buy some STP Octane Booster to put into the tank. Then you'll know that the vehicle requires premium.

If the engine seems to run fine, and the "Check Engine" light remains off, and if there's no noticeable drop in performance or gas mileage, you can continue using regular fuel unless one of these problems pops up.

I hope this has answered your question. If you have any more, please feel free to ask.

Answer 3

Take a look at the spec sheet on your motor. Look at the compression ratio in particular. When most motors reach 10.1 compression and higher premium fuel is necessary to stop detonation, ping, and spark knock.

It's unfortunate that every company could shape a combustion chamber where a reasonable high compression could be reached with no pre-combustion and knocking. Hemispherical and semi hemispherical chambers seem to be the best we have to day.

Answer 4

It probably has higher compression than most engines. A lower grade fuel has a lower octane rating which means it cannot with stand as high compression. This would cause it to prematurely ignite in the piston chamber and cause "knocking".