If you use 87, you're computer may adjust the timing, so you may not hear the knock (which normally indicates that you need higher octane) but, when it does, it reduces your mileage and will not save any money.
If you really want to go with 87 to save money -- run several tanks of 87 and track your mileage. Then run several tanks of 89 (similar driving conditions) and track your mileage. If your mileage is as good or better with 87, then, by all means: use it.
Regular's ok for your car...you're not thinking of using Premium are you...would just be a waste of money. Did you check your owner's manual? Before the SC 91 tune on my car, 89 was recommended, while 87 was acceptable...and I have the 5.7 Hemi.
There is a misconception about premium fuel that it makes more power...prem actually has less BTUs per gallon than regular. The higher octane is only to keep the fuel from detonating before it is supposed to..
Modifications like increased compression and spark advance require the higher octane or spark knock would occur...the advantage here is compression and timing result in more power than is lost from the lower BTUs..
If your car is not designed to use higher octane you will actually lose power...
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