3037 Views 12 Replies 12 Participants Last post by  JFUSION
I know I read over and over that the levels of Octane used in cars these days doesn't matter. For the last 3 fill-ups I decided to try the mid-grade unleaded which is 89 octane. In my region you can get 87, 89 and 92 grade gasoline. Well folks, my MPG has actually gone up some to 27.2 average from 26.7. The most noticable is the throttle response. I do notice a more reactive throttle response. In order to see if this is just my imagination. I am going to switch back to 87 octane for the next 3 tanks and see.. Anyone else do this? or use a higher grade fuel in their Fusions/Milan? :?
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not worth it. Your car is tuned for 87. It has a set spark table, and will sense for knock and retard timing if it occurs. You can put 130 octane in it, and the tuning will still be for 87. It is possible to use power using a higher octane fuel, since it burns slower, and the engine is not tuned for it, there is a small percentage of the fuel that is not even burned.

If youre on a stock tune, just stick with 87 octane.
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