I was wondering what everyone's thought is on this considering that 93 Octane is 20 to 25 cents higher than 87 Octane. My wife is using the 87 in hers. Are there any issues other than so decrease in mileage?

 

I wouldnt recommend it at least run 89 just because there are too many crap gas stations out there. As for me the mileage and the performance difference from 93 to 87 ( I put a 1/4 tank in once ) was enough that I will only use 93.

 

i have the 2.4L in says in the manual to use above 91 octane, so to save money one fill up i use 89 the next 93, i usually go longer when i have the 93 in there

 

supreme will run cleaner and keep engine noise down

 

Here we go again......

Of the three answers so far, I do not see any truths.

Octane doe NOT equate to MPG unless the engine is under heavy load, that is, towing, hot weather running, etc.

The HHRs have an octane sensor in the fuel system that can tell the engine controller what the octane of the fuels is so the ECU can adjust correctly for best performance.

I gotta know, what does "supreme" have to do with cleaner running and less engine noise unless you are thinking knock. You should never hear engine knock unless your fuel is really poor quality and if you do, you may need to get your engine checked.

I use 87 octane in my 06 2LT (2.4 VVT) and average 28 MPG around town and low to upper 30s on the highway depending on speed and wind load.

Back to the original question, if you use 87 in the SS you will not achive full rated power from the engine. The amount of power the engine will deliver is a factor of air temperature, humidity, barometric pressure, fuel octane, and fuel quality (E85 = bad). The average amount of horsepower change needed in order to feel it in the seat of your pants is 30HP (rule of thumb). I doubt 87 octane will reduce the power that much under most operating conditions. You are in Florida and you experience higher temperature and humidity levels than I do here in Michigan. Also, the fuel quality is by region so check your pumps and see if you are getting 100% gasoline.

My rule of thumb for my SS is 87 octane in the cooler weather and 93 octane during our summers. I don't do a lot of WOT driving, just on occasions so why buy 93 octane all the time.

 

Wait a second I said, I didnt recommend it I didnt say anything that he has to I just told him to use 89 because of crap gas stations. Basically the same exact thing you said cause sometimes people cant get to a decent gas station. Also for someone who knows the truth E85 is a good thing (NOT FOR OUR CARS) but in general it is cause it has a much higher octane rating 100-105 so future SS with flex engines can take this with a bigger increase in performance.

 

I use this and at least Mid-grade 89.......I put 93 in this last tank.....
http://mystarbrite.com/startron/cont...3/123/lang,en/

 

RTFM! If it says use 91 oe better, then the engine was designed for it. Sure you can use a lesser grade but you will find 2 results.

1. decreased power (doubt most would notice)
2. Possiblity for excessive carbon build up.

Todays cars that are designed for 87 Octane will not run better on anything higher, in fact you can experience problems suchs as stalling ect.

It's your car, you can make the decision, just do it wisely.

 

FWIW I have run all three grades in my 08 SS.

Results:
87 Octane - No knock, but it did seem down on power and I only got 25 mpg in my typical driving.

89 Octane - No issues, power seems there, 27 mpg in my typical driving.

91 Octane - No issues, good power, 27.7 mpg in my typical driving.

I'm now alternating between 89 and 91 octane fills when the tank is less than 1/2 full. I still seem to get over 27 mpg on each fill.

 

I run mid grade with no issues. Once in a while I run turbo blue and it really likes it. I use to run engines on test stands for GM, Ford and Chrysler and mid-grade was acceptable for them, so works for me.