So I have the 2.4L motor and so far my vehicle has only been filled up twice; once by the dealer (with whatever they used), and once by me (with regular gas). On the first tank I averaged about 26.5mpg and on the second so far I am averaging 28.4. For the first little jaunt (a non-highway round trip I made to get dog food, etc - about 30miles with not a lot of stopping) the gauge was actually showing an average of 36.2mpg! Until of course, the next trip and it dropped to where it is now. I know the manual says that Premium is recommended, and I have read all the posts on this topic, but what are people really experiencing. I have such a hard time "choosing" the most expensive grade of gas just "because".... Is it maybe a power difference that I am not noticing because the car is still in break-in for all intensive purposes? (and not a gas mileage thing)

 

i only put 87 on american cars.

 

Nah, the cheap stuff will be just fine.

 

Your question will prompt many suggestions and differences.

I suggest you try several consecutive tanks of each, keep consistant records, and make your decision based on YOUR results, driving habits, terrain.

Using a lower, than premium, grade of gasoline will do NO damage to your engine unless you encounter "spark knock". If so encountered, step up one grade.

Oh, forgot to say...of all the people who have 2.4 engines on the various forums, I have NEVER heard anyone indicated that they had spark knock from a lower grade of gas.

 

I agree 100%.

I did do a test way back when for mpg's. I tended to get better milaege using 91 over 87. It was a 2-3mpg difference. I guess I need to do this again the way gas prices have been getting out of control.

My wife uses 87 and swears she has had no performance difference.

 

As Snoopy said, you will get many different suggestions and opinions on this one. I have a 2LT with a 2.4 and have only used 91 octane in mine. Not sure if there is a performance or mileage difference, but I will only use premium becouse that's what is recomended, and to me the difference in price isn't that much. To put it another way, only the best for my baby.

 

Food for thought:

No matter what the octane (which only effects flame propogation rate) rating of the gas, the actual BTU content (energy available) is the same!!

The 2.4 ECM is programmed with two spark timing tables. The engine also has a knock sensor. If knock is detected from say lower octane fuel, the ECM is also programmed to "average down" between the two tables to an ideal advance setting so that knock does not take place.

Whether using low or high octane fuel, the timing self adjusts to optimize for the fuel used.

Bottom line.... It won't and cannot make a difference in fuel mileage. The ability of the ECM to operate in the higher spark advance range with higher octane fuel will result in "slightly" more power, but nothing earth shaking.

 

I have to agree with Joe!!

 

I only put 93 in any vehicle so it didn't make a difference to me that the 2.4 is supposed to use premium. Even if Chevy said 2.4 required 87 I would still put in 93.

 

I've only used 87 octane in mine and have had no spark knock issues to date.