I'm in the process of purchasing a 2005 Cobalt ss and had a few questions. What type of fuel?Is it completly necessary to use the 93 octane premium, or could I get by with the 89 mid grade?

 

I asked my dad this question and what he said was that yea, you can "get by" on it but the whole reason they recommend you using 93 is because its not so volatile meaning it won't detonate as easily as 89. if all you are going to do is cruse around town and never open her up..then why not. But as soon as you go WOT your car will prolly sputter and no get up and go. When I drove from NY to KY i put just regular ole 89 in it because it wasn't worth it to waste the extra 30 cents a gallon. I always put 93 in mine now.

 

why is gas such a big deciding factor in buying a car for so many people? use the recommended gas. so many people cringe at the idea of having to use premium. Yea, you can use 89. But you shouldn't drive it hard, and you're going to have less power and get worse gas mileage. So in the long run, you'll save money by using 93.

 

You'll get mad knock if you run any less than premium grade... The car will adjust its operation to compensate, but do you really want something as complicated as a motor to compensate for ANYTHING if you can avoid it?

 

It's a price difference of $2-3... you'll be okay.

 

ITS $2!!! They'll go bankrupt!

 

Totally agree.

I can't stand the AC robbing power when it's on lol.....There is no way i would run anything lower than 93. Hell i've driven 25 miles out of my way to get 93 rather than put 87 in.

 

I've been putting 89 in mine. Going to start putting in 93.
Should I wait until almost empty then fill up? That way there's less of a "Mix"?

 

Wait til the low fuel light comes on. Then drive another 25 miles. Sit at the pumps bangin off the rev limiter til the engine shuts off then fill it up .

 

x2 about the AC I'm assuming it's not as bad with the SC but my 2.4 is waaayy slower with the AC on, takes more revs to engage...

 

Its even worse with the 2.0 at low rpms! I used to have an 06 2.4L. We get craptastic parasitic loss from both the SC and the AC!

 

Use the right gas for your car.... The difference you save with using a lower grade is only a few bucks a fill up.

 

riiight... Or maybe I could just slam the gas in neutral and keep it pegged until the motor breaks... or maybe I should add a little sugar to the 93 octane? will it make it go faster?
jeez.

 

Yep , I think my SS/TC Idle's worse with the A/C on than my SS/SC did . I know it doesn't make much sense but the TC really struggles under the AC load . Hell when i turn on the rear defroster you can hear it work the motor harder lol.

MrFritz , I would run it down and then fill up 93. If i remember right the car defaults to the high octane map then steps down to the low octane map when it detects any knock or pinging. So If you don't want to wait for it to relearn and step up to the high map .....you can disconnect the battery and let it sit for 10 minutes or so and that should reset it to the higher O map .

I've only ran 93 in my car's so i'm not sure how drastic the difference is between the map's.......I'd guess it's pretty noticeable thou. Your motor will definitely thank you down the road thou

 

now i don't have an SS but i run mobil 1 syn and 89 octane. she runs great...i treat her good

 

well your fine since your car is only tuned for 87....unless you got a tune from trifecta and ur tuned for 89 or 91

 

Thanks Rukkee. I'll try the battery disconnect idea after filling up today. Maybe I'll see an instant difference that I can report back with. If not I'm sure its still better in the long run anyway.

And my idle bogs when the AC is on too. Huge difference. Affects first and second gear too. I try to only use it when its super hot and humid.

 

im running 94 octane my car was able to get alot more timing done before i was running 91 premuim but could get near as much timing*

 

He just meant to make it empty as possible.

There's zero benefit to running lower octane in your ss/sc.

 

Glad I'm not the only guy whose TC struggles under the load from the AC or rear defroster... I've almost stalled the damn thing a few times because of it .

 

Notice the laughing smiley face? I wasnt being serious...

 

Then my apologies.

I filled up with 93 today, but havent disconnected the battery yet to reset. I figure there's still some 89 in the fuel lines. Gonna drive a little bit first.

By the way, what the hell is up with that rev limiter. I only hit it once, but it was retarded. The camaro I had didn't have a rev limiter. It never hurt anything by pushing it a nudge.

 

1. Hey no problem. I just wanted to clarify.
2. No need to disconnect the battery cable. The car will automatically adjust timing.
3. Whats up with the rev limiter? Its retarded?

 

Yeah rukkee suggested disconnecting the battery to instantly get the stock fuel tables back for 93. I was hoping to feel an instantaneous difference instead of waiting for the automatic adjust.

Yeah. I'm not digging the rev limiter. I'd rather it push a few rpms over than interrupt my shifting.

 

I don't know exactly how many cycles it takes, but I am pretty sure that it is every time you shut the car off and start it back up that the car uses the high octane map.


When the car detects knock it will reduce timing to somewhere inbetween the high octane and low octane maps. After a certain amount of time with no knock the car will default back to the high octane map. If a certain amount of knock is seen within a certain amount of time then the car will switch over to the low octane map until the car is cycled.