Simply because 2ZZ-GE has a compression ratio of 11:5:1 and the user manual (and fuel lid) says "use octane 91 or higher".Mooch said:What do you usually put in it?
I had a car years ago in which I used 93 octane and it cost me hundreds and hundreds of dollars to try and find out what waswrong with it. I was told the 93 octane had clouded up my spark plugs and filled them with deposits. They were a mess. When I sent one back to Aamco who I bought the gas from, they said "I''ve never seen anything like this before."