[NMuzj100]

I think that there is no possible damage that could come of running regular (so long as you don't get knocking or pinging - and that is not likely) but it will be impossible to get the maximum performance from the engine. The ECU will adjust to allow the best operation for conditions.

The "Premium Fuel Only" sticker is there to keep people from putting in low test gas and then complaining that their crusier doesn't make the promised power. Wish I had a 4wd dyno to measure actual peak power lost when running lower octane/compression levels ( my guess is small loss).

Engine gurus - Will this loss theoretically be throughout the power/torque curve or only at the higher levels ?

My $.02 ( uninformed) - The ECU might adjust very quickly to the lower or higher octane level just as it does temp/air density ect...( in fact I doubt it measures octane independently [no octane sensor] but calculates it from other known variables) The only area that it probably takes time to adjust to is to driver imputs so that a temporary wild streak or driver change doesn't rapidly alter the vehicle's "feel" to the driver.