Dumb Octane Question
 

My dad borrowed my car the other day because his piece o crap chrysler product was in the shop and when he was done using my car for the day he decided to top off my tank for me (nice guy!). I had just under a half tank of 93 octane in it when i gave it to him, and he said he put 87 in it to top it off with... all though still thankfull when i asked him what he put in it he was your kidding right you dont need to put premium in that lil 4 banger. i wanted to tell him... NO..MAKES A PRETTY BIG DIFFRENCE....but didnt want to sound ungreatfull so i bit my tounge and just said yeah your right thanx dad. any ways my question is now that the gas has mixed is this bad? ive never mixed two octanes together?

I dont think the 2.4 needs 93.

But to answer his question it mixes. If you have a gallon of 87 octane and a gallon of 93 octane and you mixed them. You would have 2 gallons of 90 octane.(ok, not quite that simple. But it would be somewhere in between.)

So if he just throw a gallon or so in there you wont even notice. If it was more 87 than 93 go ahead of by some octane boost from the gas station or parts store.

2.4 definitly does need need 93, dont waste your money, i was running my ss/cc on 87! the only reason i run 93 now it because it is better for forced induction and it burns slower when i beat on it aka making my mileage better

cool guys thanx for the info!

2.4 you don't need 93 or 91, for non FI cars mid-grade (89) fuel is the best.

As for mixing I would not worry about it. Mid-grade fuel at the pumps comes from half 87 and half 91. Your car could hic-up here and there if you change the octane you usually use.l

i wouldn't worry about it unless your manual says to ONLY use 91 octane or above.

Premium recommended but no required for either the 2.4 or 2.0 ecotecs.

Your going to lose timing when you shift to the low octane spark maps and lose power. It's not going to hurt your engine, but you will lose HP.

running a lower octane won't hurt anything in the 2.4... you'll notice a slight performance difference if you really get on it... but otherwise... bah... don't sweat it... and don't waste your money on octane booster either. Just drive it till it's empty and fill back up with good ol' 93 octane...