it was turbo blue 110, but I don't recall what type-they offer leaded and unleaded IIRC. But it doesn't matter anyway because I am missing 2 o2 sensors and the other ones are turned off. Plus, my car has no cats so it won't be messing those up either! It's had quite a few tanks of 93 run through it since then, so no worries!

 

Let me start by saying I am happy to pay for 91 octane except in Colorado. I have been told by a very highly recommended corvette specialist ( not a dealer ) that at altitudes above 4000 feet I should use 85 octane and throw in an octane booster every 3 or 4 tanks fulls. It's NOT a gas cost saving issue. At 6000 feet ( Colorado Springs) the alcohol in 91 octane merely causes the O2 sensors in the cats to become "sugar" coated. That then triggers the Check Engine light to come on and the PCM code of P0430 to be displayed - TWC Sys low efficiency Bank 2. The Dealer then wants to charge $3700 to replace both cats. I only have 37000 miles on my 04. I bought it used in Chicago the day after Christmas 2012. Adding fuel ( pardon the pun) to the fire, the P0430 code is followed by an H and a C. Checking back, at 16000 miles from the service record the entire exhaust system was replaced. OUCH. SO do I have a bad cat or not? Didn't go the expected 100,000 miles according to the code. SO, I am putting my faith in the local non-dealer expert who runs 85 octane in his 2005. I will run 3 tanks of 85 octane and if the Check Engine light doesn't go out I will have the expert look at the O2 sensors and fix accordingly.
Any thoughts? I see where folks are calling other folks idiots for not using 91 or better but they never state where they live.
Thanks in advance for your reply. The dealer of course never heard of this and I even have Bolling Green looking into it.

 

I agree you can get away just fine with lower octane in higher elevations, But watch out if you go to sea level.

 

Sounds like I need to start filling up with 92 in VA for under $40. Down here in NC, I can't fill up with 93 for less than $60.

.

 

amen...enough said

 

That was 2.5 years ago when this thread was started...

 

ET makes a good point when looking to buy a C5, what if previous owners ran cheapie fuel? How would you ever know, unless seller was honest enough to say so.

I run 91 here in Colorado, I'm at 7200 ft and drive fro 4500 to 10/11000 ft all the time, one of my favorite runs goes from here up to 10500 back down to 4800 and back again. Haven't had any problems as of yet.

And really, I guess if your pockets are phat, you really dont give a rip one way or another, me I saved up long and hard for my vette, and ill be damned if I'm gonna run 87 in it. It will sit if I can't afford the fuel for it.

 

I haven't done this, but I'm curious, does this math actualy hold true?

1/2 tank 93 octane + 1/2 tank 89 octane = 91 octane

 

I'm at 5,500 ft. and always ran 87 octane in most of my vettes. Got 90k on my 02 now and I've never had any engine problems in any of the cars fron running 87 octane. I average 32 mpg on the highway and 26 mpg around town. I've been called all sorts of names on here for doing it, but it's my car. I've also been told because of the altitude we can run lower octane gas here by more than one mechanic. I've been doing it for over ten years (in vettes) and I'll probably keep doing it.

 

Ahh! I gotta start reading the dates before I respond! Thx for the catch ...

.

 

I topped off the tank at Road America (ALMS)Saturday. Its was $9.69 a gallon (98 unleaded octane)It was worth the money just to drive thru the pits. Two fellows with full fire suits and their equipment standing on either side. I'm glad I did because Sunday I did a couple laps on the track. Doug from ECS told me If you going to pound on it, an extra 40 or 50 bucks (higher octane) is cheap insurance. Normally run 93 everyday day driving.