Quote:
Originally Posted by fanforever1986
2000 VW Jetta VR6
What are peoples take on cars that are suggested to take only 91 or higher octane gas?
Does it actually matter? I've been putting in regular lately and the car doesn't run any differently. Gas is just too much money on the west coast right now.
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The octane of the fuel describes how much energy is required to detonate the fuel. So the higher the octane, the more difficult it is for the fuel to detonate.
This is desirable for newer engines with higher compression in the cylinders as it helps to prevent premature ignition (ignition before the spark).
Running with a lower octane means the gas could ignite before it's supposed to (called knocking), which of course isn't very good for your engine. Most modern engines have sensors which detect and adjust for that by changing the timing of the engine, but the negative side of that can be either reduced effeciency and/or reduced power.
One thing I'm not sure if they take into account is the elevation.. we're a pretty high city, and the higher you go the lower octane is required to have the same anti-knock protection.