Is it really necissary for the 2.4? I just bought a 2008 with the 2.4 and wasnt aware that it requires 93 Oct. It was an old rental car, so I gaurantee it has never seen 93. I made an 1100 mile trip this weekend and ran 87 the whole trip. I experienced no spark knock or anything. Whats everyone else running?

Rex

 

No.... My mom has a G6 with the exact same engine, and it only requires 87. A lot of people just run regular in it...

 

I run 87, 89, 91, 93 No problem.

 

it is not necesary...i've ran many tanks of 87 and 93...i noticed a little better performance and a small increase in mpg , but not enough to offset the cost...but , if i drove 275 miles a week opposed to the 275 i drive a day , i would probably use the 93 since it's only a few dollars more...the computer adjusts the timing so that it makes little difference.

 

I've never understood why the 2.4 in the HHR "suggests" premium, but not in anything else that I know of.

 

Ok thanks. I looked and the compression is 10.5:1 so that may be why they suggest 93. The wife only drives 200 or so miles per week so I told her to start putting 93 in and gonna switch to a synthetic also.

Rex

 

I finally ran out the tank of 87 octane with which the dealer filled my tank when I bought it. I thought it would never run dry. I filled up with 93 octane, and I can tell a difference. My 2.4 has a small flat spot off idle when you floor it with 87 octane. With the 93 octane that flat spot is gone. So, in my car, I can certainly tell the difference. It makes sense that 87 octane in 10+ points of compression is going to result in the timing being delayed.

Also, I have noticed that with the HHR, Chevy did one of the best gearing jobs I have driven in a while. It has a steep first that masks the fact that it is a four-cylinder very well. That tach really sweeps fast in first. Also, it is eager to downshift underway, which again makes the car feel like it has a lot more than a 172 bhp Four under the hood. This is the first 4 cylinder I have owned after six consecutive V-8's - from a 4.6 Modular Ford to a 440 Dodge, so maybe I have a slightly different perspective than some.

God Bless, Marc

 

Well I went from a 1995 Mustang GT with an Auto and 3.73 gears and I am still impressed with the acceleration of the HHR.

Of course when want to really accelerate I take my other Mustang to the track it has an auto and 600+hp. It accelerates pretty well

 

The first thing to do to learn how to operate your vehicle is to RTFM. This can be found on-line for those who don't have it.

From memory the 2008 manual says the higher octane is "recomended but not necessary". I assume that GM knows better than I do.

A question I have posed here, that no-one has seriously dealt with is, given that much of N. America is at a high elevation, would the lower absolute cylinder pressure produce as good a performance with lower octane when driving in the thinner air?

 

Nobody wants to pay for premium including me, but it does make a difference in performance. GM does not benefit by anyone using 93 octane but they know you'll be down on power a little with 87. Only you can decide if it's worth the extra cost. It's curious to me how in these forums that some people are willing to spend lots of money on other bits for slight gains in power but question the advantage of high octane fuel for optimum everyday performance. I'll take all 175 hp...the car needs it!