I have read various articles on which type of fuel, regular or premium, should be used in the Cobalt turbo. I read that GM recommends premium but it states that it is NOT necessary. I have 4000 miles on my '08 and have been running nothing but 87 octane regular with no problems. Should I use the premium or stay with the regular? What are your thoughts?

Please, only folks who really know what they are talking about reply. I have scanned this forum and found many people putting in their opinions when it comes to providing "actual" data. I profess I am not up on the newest technolgy on cars, as I come from an era when all you had to do was change points and plugs, do a tune-up every 30K miles, set the timing, adjust the dwell, and you ran for another 30k. It was a time when you could actually get to all 8 spark plugs due to the massive amount of space in the engine bay. Today, well it's an entirely different story.

Thanks

 

premium man only premium

 

Here's kind of how I understood it.

Use premium any time you can get it. IF by chance you are on a trip or something, need gas, and the station doesn't have it. You CAN use regular but I wouldn't drive the car hard at all.

I see it more of a "just to get you by" fuel. Otherwise, stick with premium. It's not that much more.

 

use only premium when you can, only use regular if you absolutely have to

 

The car has a knock sensor...

I run midgrade, since with 10% ethanol it is cheeper than regular out here. I get no knock retard with midgrade.

 

87 is not good. mid grade or top grade only.

 

91 or 93 if its available in your area.

 

Premium is recommended, like what it said in your manual (if you are the 5% who actually read it).

Otherwise, I say 89 is absolute minium. It only cost few buck more a tank, if you can spot it, go with 91~93

 

Im a tech at a chevy dealership and i own a 08 cobalt tc. i talk to GM tech line which we have access too if we have problems with veh we cant figure out. they said u can run 87 but recommend premium, if u run 87 u wont get the full HP out of the car. but me i only use premium fuel only and thats what u should run.

 

I have tried regular, and premium, and I reccoment the premium!!! in my car, the regular 87 octane gas seemed to work well enough, but when I really romped on it, the engine pretty much quit pulling just before 5K rpm. when your running on fumes, try filling er up with a tank of premium and then go out and give er ****! you may be amazed at the difference!!!

 

My car is just an LS, so I was filling with 87 with 10% ethanol at husky (AMA dollars there). A couple weeks ago I read that the car will actually change your ignition timings to prevent knock, which degrades the performance of the engine. I've started filling with 89 with 10% ethanol, and I've noticed a considerable change. My fuel economy has improved by .3 L to 100km.

 

this is true! if the knock sensor detects detonation, the ecu will adjust the timing, and add more fuel to compensate! hence the lower mpg! midgrade gas should be fine for a non boosted engine! what's the compression ratio on as LS? is it 9:1 ?

 

The engine controller will provide best performance on the recommended pump premium (91-octane or above) gasoline. In addition to high boost pressure, the LNF runs a pretty high static compression ratio which generally makes an engine more prone to detonation/knock, but the direct injection slightly counteracts that and provides a little better detonation resistance than a port injection setup. It also has two knock sensors but fact remains you have to get knock for it to be detected and the computer to react to it. If you do run 87-octane you will get more knock under heavier loads (such as when under boost and accelerating hard) and the computer will adjust things like timing and boost downwards in an attempt to stop the knock from occurring.

If you are just doing light load cruising and a lot of highway driving it may not be bad to run lower octane fuel but if you hammer the car hard and operate under certain conditions (hot weather, driving up steep elevation passes, etc.) the recommended premium fuel will provide much better performance. You probably won't kill a stock engine from running lower grade gasoline for extended periods but I wouldn't do it.

A couple things for you consideration. If you're curious as to what affect it has on the engine you could invest in a scan tool or scan gauge that can display ignition timing advance and degrees timing of knock retard and compare them when running the two fuels. You should see that knock is quite a bit more prevalent on the regular grade and overall advance has been reduced. Even on pump premium you'll see some knock under higher load but it shouldn't be nearly as much as lower grade.

The next thing to think about is how much of a difference you're saving by trying to pinch pennies. Lets do the math and say the average driver goes 15k miles per year and averages 25 mpg. That means you'll use 600 gallons of gas per year. Pump premium usually ends up being about $.30 more expensive so if you multiply that by the number of gallons used that comes out to $180/year or $15 a month.

Think about how much payments, insurance, and general maintenance runs the average owner along with other cost of ownership factors like how depreciation figure into total cost of ownership and that $15 is a pretty small portion. Sure, gas isn't cheap and when times get tough every little bit can add up, but if you can afford a brand new SS Turbo and can't spring for the right fuel to maximize performance and run optimally (especially when it's not that big of a difference) it may be time to reconsider your priorities.

With that said, I personally wouldn't run regular unleaded in any of my turbocharged vehicles but modern engine controllers are pretty powerful and you probably won't hurt anything. Start modifying the car or hammering on it hard all the time and you may reconsider stepping up to the right fuel.

 

There is no benefit to run 87 NONE. It may cost more up front to run the 91+ but you will see an increase in your fuel mileage that will out weigh the cost and end up saving you money by running the 91+. People can say you will be fine as long as you stay out of boost but that just isn't going to happen and the result is poor fuel mileage with the 87. So really in the long haul the 91+ will save you money. If you don't believe me just keep track of it and that will speak for itself. Here is a good site to accurately track your results even better than the factory monitoring system: https://www.fueleconomy.gov/mpg/MPG.do

 

Thanks! I got registered. 24.7 mpg average since I bought it.

 

I posted this in the fuel milega section but it aplys here also.
This article shouuld help explain things
http://buzz.consumer.myride.com/u.d?...M5z9jTSEE=5341

Clif notes
If you car recommends 87 use 87
If you car recomends or required premium use premium your get better performance and milage.
Yes the SC and TC will run on 87 but you will likely loose mpgs and performance. And if you read the article it will likely be cheaper to to use premieum per mile.

 

Only Premium Dude And Nothing Less
You'll See Better Performance Out Of Your Turbo

 

Any time.

I started using this site over 2 years ago it works very well. For some reason I stopped after I lost a few of my receipts on a road trip. I wish I would have used it after I put my stg 2 kit on my SC and getting 30mpg on avg. Right now it seems that my stg 2 SC got better mileage than my TC does. I am going to do a much better job with the tc.

 

Race fuel + no cats+ big turbo+ tune

 

my friend has a tc he runs only 93 yes ive actually never seen under 93 for premium where i live i love it i have a 2.4 sport and i only run 93 the only time i dont is if i have a lil over half a tank and fill up i use midgrade (89) kinda evens it out around 91 which is still perfectly fine to run in my engine yeh the 2.4 also is recommended to run premium

 

I run 91 because it's all most Canadian gas stations have. When I'm at school in Southern Ontario and I'm near a Sunoco, I get 94 octane from there.

 

I wish there was a Sunoco around where I live!

 

when you are driving and fuel is coming out of your exhaust you should probably use premium. I guess the main rule is that you get what you pay for. WHen you have upwards of 60,000 miles compare it with someone's that has the same that has been putting in higher octane levels. I guarantee you that the car that has been running on higher octane will run better, and with the same mods will be faster. If you're gonna have a sports car then why pay for cheap gas??? ****, i have a friend who puts 100 octane in his car every now and then because his car likes it.

 

I found a recipe for a fuel (I have not used it). Use 1 part Xylene (octane rating of 119) with 3 parts 91 premium and get a fuel with 100 coctane rating. Today, there are places where Xylene is cheaper than gasoline, which surprises me since Xylene comes from the crude oil refining process. I have no experience with the mix, just thought someone might be interested. I have hearde of people using this in racing snowmobiles, ATVs, etc., with compression ratios as high as 13:1.

 

Nothing less than 91.

Have you found test results from running it on daily street driven cars? Sounds to me a lot like the guys saying they make their own race fuel.

Links to this data?