What fuel does the owner's manual for the 2.4L ecotec recommend? I'm assuming it will take 89 octane like the 2.2, but perhaps being an SS higher octane is recommended? Also, if the car requires more than 89 octane, would running 89 octane damage the engine? I know performance would be hindered, but would the lower octane actually do harm to the car?

 

Recomended is 91 octane. That will give you all 171HP.

GM claims running 87 Octane is acceptable, but you will experience a power loss from doing so. I would b afraid of an engine knock condition developing running this. GM must have tested to make sure that this doesn't happen, so you should be OK.

So 89 should be good then, just less power.

 

look in the manual it will tell you that and meny other interesting things to.

 

Yes, let's all read our manuals. It's amazing the wealth of knowlege the builders of our car have left for us to find! It's in the glove box, no cave diving for us today.

On the SS/SC, my manual says that best performance = 91, but requires at least 89. No lower than that... minimum of 89 is pretty standard on all new cars these days.

 

I do not own a 2.4SS, which is why I do not have a manual to reference, but thank you for your input.

 

the 2.4ss manual says 87 is okay but 91 is preferred and would give increased performance

 

My manual says 87 is fine for the 2.2L... no performance increase with 91 though (or 94 which we can get here )