Originally Posted by
OwManThatHurt
well decreased performance is the first thing you notice, especially in a turbo motor. i've heard of other problems arising as such as pre-detonation or not igniting all the way or something like that.
Do you mean pre-ignition or detonation? Pre-detonation isn't a real word..
Low grade gas isn't as stable when it combusts, which is why pre-ignition (before the spark plug fires) and detonation (after the spark plug fires) can sometimes occur. You have to have a knock sensor for an ECU to retard timing or lower spark energy though, so if you have an LS or whatever engine without a knock sensor you will have to tune a little more carefully.
Honestly there isn't any reason why you need premium gas all the time if you're just commuting or whatever. If the engine is driven normally, at low loads, there isn't much danger with a standard tune. When you do actually want to use the full performance though, it's nice to have the right gas on tap though..