The CX-7 has a turbo engine. Here's a quote I found regarding turbos:
"Living with a turbo is a lot of fun, but there are a few important things to take into consideration. You should recognize that your engine will generate more power by burning additional fuel, so you can expect to spend somewhat more time at the pump. You'll also need to use premium gasoline in order to prevent pinging or pre-detonation."
You have an engine with a high compression ratio 9.5:1
Then you have a turbo that boosts to realitively high boost leves of 15.6lbs of boost.
Together these mean that you have very high cylinder pressures.
High octane is required as its primary function is to not pre detonate under mechanical compression and wait for the spark plug to set off the air/fuel mixture at the right moment.
If you run low octane gas, you will cause detonation to occur. The sensors will note this and radically retard your timing killing power and killing mileage. This in turn will mess up the shift points in your transmission.
Thus, never put anything but 91 or higher in your car....
If you do and it start to run poorly, don't expect it to be warrentied at your dealer
A forum community dedicated to Mazda 3 and all Mazda vehicle owners and enthusiasts. Come join the discussion about MazdaSpeed performance, modifications, classifieds, troubleshooting, maintenance, and more!