Originally Posted by WMichaels
The key is that we have 10.0:1 compression. That's what dictates the higher octane fuel. Even retarding the spark won't change the octane requirement with a compression ratio that high. Lower octane fuel will predetonate (ping) and can and will do severe damage to your valves and pistons (burn and pit them). Lower compression engines can use lower octane fuels.
Wes,
But there are always exceptions. My wife has an 01 Ford Escape with a 3L V6 engine. The compression ratio is 10.0:1. The recommended octane is 87!