Manual says 87 octane or higher. I have read that if engines with compression ratios of 9.3 : 1 or less will safely operate with unleaded 87 octane fuel. Engines with higher compression ratios usually require higher octane fuels. As www.msn.com data, the 2004-2006 Malibu LT 3.5L V6 compression ratios is 9.8:1. Do we need to use 89 octane or even 93 octane?

 

I would follow the manual. it can't hurt anything in the car to use a higher octane, only thing it hurts is your wallet.