urbexHHR

There is a reason that GM states in needs that fuel. Yes, it will retard the timing and you will lose power and economy, but you will also have abnormal combustion, like pre-ignition.

bartSS

dude this is like beating a dead horse lol. You keep telling them one thing and they will tell you that $5 more a tank is too much. How about you skip going out to lunch one day a week or smoke less cus that adds up quick too. Ever think about that??

urbexHHR

Mmm...no. Octane is octane. There are two types. Research Octane and Motor Octane. Add the two together and divide by 2, and you'll get the grades listed on the pump.

LewiSS

Mine averages about 25. I run premium. I have a stock SS. I would love the extra power of the Stage 1, but have heard too many horror stories. I will stick with stock. I believe the mileage/premium gas cost/performance ratio is a very good compromise. I went from a Toyota Prius which barely got 35 MPG to this. I couldn't live with the lack of performance, inability to even move on snow, and brakes that didn't. I gave up some mileage to get the power. It's really up to your own sensabilities, what you want to spend your hard-earned limited cash on, and what you want to compromise. If you want mileage over performance, get a LS Panel - they're lots of fun, look great, and run fine - but not anywhere near the performance of the SS.

hyperv6

Sorry I ment High priced not high test. I know what octain is and just typed too fast on a phone and missed a word.

urbexHHR

Oh, that makes more sense. I misread it, thinking you meant all grades are better or something...lol. I see what you meant.

hyperv6

The fact is that the engine does not need that fuel. It should have it to run the best it can but the electronics and sensors has made it to where it is an option to run either with no Pre ignition or detonation.

If it was unsafe to run regular it would not give you the option like on the old 3800 SC Series II.

In my SSEI it said I could use regular only if no high test could be found. It also stated that if I did use regular not to do a WOT runs and to drive conservitively till I can get better gas or perminate engine damage will occur.

Todays cars are very advanced and can do things once not able. GM only looks at the options and tries to in most cases give the owner the ability to choose what they want.

Note the Volt used premium only because they know that for some drivers it may be in the tank longer and it will degrade less over the time. This was a real issue for the engineers as they know most buyers of the Volt are trying to save money on fuel. If I had a Volt to drive to work and back I could have a tank of fuel for 6 months and never use it. I would use more just because the engine will run a little in the winter to make heat for the car. Note too the engine will cycle on to use up some fuel once in a while so it does not get used for people who have short drives.

I deal with a lot of the new technologies in my job as these systems in the performance aftermarket can be used to make more power. The parts my company sells often effect the gas requirements after install.

urbexHHR

Not to be a douche, but do you have any proof of that?

Gas Man

I'm with ya Bart. I think there is 2 very different POVs on "putting their foot into it".

hyperv6

No problem questions like this are fine. Also there is enough info in print and on the web from reliable souces that state the same.

The proof is in your owners mauel. It stated on the 2.4 and 2.0 to use premium with 91 or higher octane. Note it also says you can use 87 octane or higher but you will notice a slight reduction in acceleration and you might notice a slight spark knock. They then go on and state not to use 87 or less as you may hear a heavy knock and to get better gas as soon as possible or you could damage the engine. In my 08 manuel it is page 5.5.

A slight knock is not damaging as it often is very little and the timing is pulled as soon as it hits. Heavy and prolong knock will break things like pistons and or rings. That is just common knowledge any engine builde or hot rodder will know. Too much timing and too little octane will mess you up every time. In the old days to move timing you has to move the distributor. Today the computer does it based on many factors like knock sensors etc and predeterminded conditions programed in.

Also any dealer can and will inform you the lower octane will not hurt your 2.4 or 2.0 in stock trim.

In my old Pontiac SSEI manual it stated clear that you could only use less than 91 in emergencys and not to do any wide open runs. In other words don't run the boost up on the super charger till you get better fuel. It did state clearly damage can and will occur. My 04 GTP with the newer engine is like the SS and makes it plain that you can use either with no penalty other than less power. Pontiac even used this point in their printed marketing materials. They did not make a big deal out of it but they did mention the ability to use either.

I was invited to a Chevy Marketing Managers home in Detroit and got to spend some time with him talking cars. He at one time was incharge of the Monte Carlo and Impala lines. He showed me they were getting the Series II Supercharged engines and was not happy as he felt they should get the Series III Superchaged engines as they could run regular as an option. He felt it was a bonus to garner more sales and not scare off prospective buyers. Selling more cars is the name of the game.

In a car like a Vette or CTSv premium fuel is not really a factor to these buyers as money is not an issue. But with a lower cost Chevy it does become a factor to some buyers. It is like my wife, It cost her $50 to fill her GP and while the premium is little more she does not want to pay a dime more than needed if it will not hurt the car. These are the people GM wants to not run off. Many could care less about the 20 HP they are missing as 240 HP is as much as the old Series II we used to have had and the 260 HP to here is not any big deal. She can still haul A$$ in the car like she used too in the SSEI and is happy.

Also you can contact the many companies that make performance programers. They do much the same as GM using the same sensors to adjust to the fuel being used. Here is a dyno sheet on a Chevy pick up from Hypertech. They make a programer that can use premium or regular fuel and in this case the timing and fuel can be +28 HP on Prem or +16 on reg. It is your choice. They too want to appeal to as many buyers as possible.

http://www.hypertech-inc.com/performance-gains.aspx

Like I have said there is no right or wrong when the car is listed at a Premium recomended. GM Engineers would like you to use the best as it will give you the best all around performance. But the GM marketing people also want you to know you can cop out and use the cheaper stuff if you like with only a penlty of lower power.


One other factor that is in play over the electronics is the new Direct Injection systems. You can run a car with more compression or boost with less knock. The fuel shot into the cylinder really works as a cooling agent that keep the temps down and prevent knock at lower levels. Also it delivers the exact fuel at the right time for the engine to take full advantage of it.

While the electornics today can be a pain if they go wrong most are doing some amazing work in many of the new vehicles today. Electronics, DI and VVT are why we can get 290 HP out of 2.0 liters at 23 PSI in a daily driver. 10-15 years ago it would have been a hand grenade even on rocket fuel.

A Ford engineer told me a long time ago that they build cars not to fool proof them but to idiot proof them. I think the latter also has a lot to do with GM's choice to use a duel system to prevent engine damage and the abiltity to use either fuel.