Hey guys im new to the forum. Im going to be soon purchasing my great aunts silver 06 Monte Carlo SS. Im very fortunate to be purchasing this car because it was very well kept and has only 33,000 miles on it. My main concern is she has ran 87 octane in the car since day one. In the owners manual Chevy recommends the LS4 run on 91 octane or higher. Im not concerned about damage to the engine because it was driven lightly by an old lady. This leads to my question, when i get it, will changing right to 93 octane do any damage to the injectors, or the engine in general? I was told by two different people that switching octane like that could cause damage. I call bull. But I thought I might as well ask here.

 

I think you're right on all counts. 91 isn't required, it's only reccomended. Even if she were beating on it, it would just pull timing and have less power. The engine will be just fine.

Switching to 91 or better won't cause any issues. Only time I've heard of issues changing fuels is going from regular gas to e85 after a lot of miles. Supposedly it's a better solvent and flushes gunk from the tank into the filter.

But you're going from gas to gas, the fuel is the virtually identical. It's definitely worthwhile for the extra power. Sounds like you're getting a sweet deal!

 

I bought my '07 SS with 38K miles on it, and no idea what fuel had been used in it since new, so it's possible that 87 was used. I have never put anything but 93 in it for four years and never had any issues. Now all I burn is 93 ethanol-free. She runs pretty sweet.....

 

Sounds like a nice, low-mileage car!

I agree with the others here. I bought my 06 SS with 63k miles and have no clue what fuel was used prior. I did run 87 in it when I first got it and saw/heard no real issues. The manual does recommend 91 octane and that if you hear spark knock to run a higher octane. I didn't have any noticeable knock on 87. After the first 6 months or so, I jumped up to 93 and have been running that ever since. You will have a noticeable performance gain with the higher octane - runs smoother and has quicker response.

 

Hello and Welcome to the forum!!

You suck, what a great deal you are getting. Jealous!

 

I often think about tryin a tank of ethanol free gas to see if my car runs any better or worse lol

 

Eh, it won't be noticeable. The ethanol changes the effective burn rate, but definitely not enough that your car would feel it.

It's a bigger change on older cars, where they are just not meant to be near ethanol.

For my 68 Camaro, I travel to 1 specific gas station in the area because it is ethanol free.