Good info to have. Thanks

 

I took a 3000+mile trip last year in my old 2009 C6 automatic 2.73 rear and most of the trip was cruise set to 74.

On 91 octane 2 tanks back to back I averaged 29.8 on a carefully filled tank to the brim using a calculator. Car computer was always showing higher 31 to 31.8 mpg.

Then I ran 87 octane for 2 complete tanks. First one actual 28.3 mpg and the second one on level ground 26.5 mpg.

Refilled with 91 octane for the rest of the trip and 28.7, 29.8, and the last tank 31.1 mpg.

I noticed it took a while for the cars computer to adjust to the lower and higher octane gas.
I never noticed any spark knock as I did not push the car on the 87 octane.

Anyone who think that running 87 or 89 octane in a corvette makes no differance is just kidding themselves. Back in the early 60s and 70s I raced at all the local tracks and held many records. We got great performance by using aviation 130 octane fuel so we could jack up the timing for more power.

Today's cars use modern computers to make those adjustments for us by using a knock censor. It can detect a knock before it is even audible.

Jumping on the gas after switching from 87 to 91 octane will not show the performance differance, as the computer is quick to retard the timing based on knocks. It sometimes takes a full tank before it advances to its normal setting.

In the 70s thru the 80s I was a car dealer and ran 2 speed shops

Now retired and waiting on my 2015 C7 A8 Z51

 

I just got back from a 6418 mile road trip out to California, Oregon, Washington, Idaho, Wyoming, etc and found premium gasoline at every station I stopped at. I couldn't find 93(which my C6 Z06 likes) but 91 was available at every station(except for a Phillips 66 in Edmunds, Ok that only sold 87, but the station across the street had 91). Finding ethanol free gasoline out west is a problem.

Oh, and at higher altitudes, your car does not need the higher octane gas as it needs down close to sea level. 91 at 5,000+ feet is the same as 93 at 500 feet.

Not once did have to gas up with anything lower then 91 octane and I did some driving at 10,800 feet. GM recommends 93 in the C6Z06 where they recommend 91 in both the base C6 and the C7. Believe me, the engine is working harder pulling the grades in the mountains vs cruising along on an Interstate highway and I did it with 91 octane that I had no problem finding.

The lows....




The highs....

 

What they both said! No worries at all, have a BLAST!!!

 

Driven a lot of Utah and some of Wyoming and never had a problem finding "premium" (91 octane or higher)

 

You dont need premium fuel owned 17 corvettes the later models surely can use reg gas the earlier models just spark knocked if fuel grade was too low

 

Things have changed over the past 17 corvettes you have owned. On the 2013 C6 LS3, GM recommended 91 octane but said it was okay to use 87 or 89. The LS7(Z06) and LS9(ZR1) required 91 octane but GM recommended 93 octane and said anything lower than 91 was a no-no.

For the 2014 LT1, GM requires(not recommends) 91 octane and anything lower is a no-no.

For those that have owned 2013 and older Corvettes and are making recommendations based on the ownership of those particular cars, you should read the 2014 corvette owners manual where it says on page 9-51....

"Use premium unleaded gasoline with a posted octane rating of 91 or higher. If the octane is less than 91, you could damage the engine and
may void your vehicle warranty. If heavy knocking is heard when using gasoline rated at 91 octane or higher, the engine needs service."

Nowhere in the 2014 Corvette owners manual did I find the statement "Use what ever gasoline that the Corvette forum tells you to use."

 

Just returned from a 3500 mile trip in the C7. I used all grades intermixed. Mostly 87 when headed for a long day at 70-85mph, fairly flat roads. Never noticed any difference. Like a previous poster said, in 4 cyl mode, you could probably run anything.

By the way, same applied with my C6, mixed octane ratings all the time. Never could tell any difference!

 

I have driven my two Corvettes, over the last 15 years, through the Yellowstone, the Tetons, Black Hills of SD, and across Utah and all over the Rockies of Colorado, many times.

Never once, did I have trouble finding Premium fuel. It may be 91, instead of 93 octane. But it's fine.

I've been to the Yellowstone 11 times, several in my Corvettes, and in rental cars. Start each day with a full tank, and drive about the park and mountain roads all day. No worries at all, for you on this. I was there as recently as last Sept/Oct.

You'll be without cellular service many places. But there will be premium fuel at the service stations at all five exits of Yellowstone. And all throughout the mountains. I"m not saying, if you look hard, you couldn't find a little mom & pop station in some remote area, without premium gas. But I never have, yet.

Go, enjoy; Corvettes rock in and over the mountains and National Parks.

Don

 

I lived in both the areas you mentioned and found no problem getting premium fuel....it's not the wild west or a foreign country you know.....

 

If your knock sensor takes a dump, you could indeed damage the engine. Not worth the trivial savings you get by going cheap with fuel. Don

 

Great pictures. Welcome home btw.

 

Uhmm . . . How often have we heard of a knock sensor taking a powder ?

 

Have you looked at the label inside your fuel door?

 

I live within 50 miles of Yellowstone, and drive through it on a regular basis. I'm not having a bit of trouble finding 91 Octane. Come on guys, you have a car that will do a minimum of 400 miles on a tank of gas. If you're really that worried about 91 Octane, fill it up in the bigger towns. (Big towns in Wyoming means 10,000 people or more, so I think Wyoming only has two big towns.) Somehow, the rest of us manage to survive!

 

I have no idea. Is it worth the risk? 1000 gallons, 20,000 miles of driving and you might save $350, bad trade in my view.

GM may well see signs of detonation if the engine were damaged and refuse to repair it at their expense. Don

 

I filled up with 91 at an Exxon station in Livingston, MT, before I took US89 down to Yellowstone, and filled up again in Cody, WY with 91 before going north on Hwy 120 to Hwy 296(Chief Joseph road) to drive on US212 and filled again with 91 in Billings, MT. Filled up again with 91 at a Phillips 66 in Spearfish, SD. Topped off with 91 in Mundo, SD and again in Sioux Falls, SD, and again just south of Kansas City(with 91). When I got home, in Springfield, MO, filled with 93 ethanol fee at Conoco. When I'm out in the boonies, I usually top off my tank when it gets down to a half tank(to be on the safe side).

 

How many times do you think I've had the fuel door open during the last 34,000 miles I've driven my 09 Z06? What's your point?

Where does it say anything different than what I posted?



Oh, and the owner's manual goes into additional detail as what fuel is required in my Z06, as it does for the base C6 and the ZR1, as well as it does in the owners manual for the 2014 C7. How many times have you looked at the owners manual that is in the glove box of my Z06?

BTW, the sticker on the inside of my fuel door does not say "Use what ever gasoline that the Corvette forum tells you to use." and I doubt it says that on the inside of the fuel door on the C7.

 

Thanks. Heading out in a couple of days to do a road trip with 15 Corvettes to Mackinaw City, MI, hitting some car museums on the way then up into the Michigan UP, then back down through Wisconsin to have lunch in Wisconsin dells, visit the Circus World museum in Baraboo, and then down into Illinois to visit the Illinois Railway Museum In Union, IL.

Road trips in Corvettes are great fun(especially when you have a group of them going). I hope the first time owners of the C7 will check out their local Corvette clubs and plan to do some road trips. I do use pure-gas.org to locate ethanol free gas stations when I'm traveling.

 

Also, there's no question that performance will suffer with lower octaine gas. Doesn't make much sense to pay a premium for a sports car, and then try to save a few bucks by buying cheaper gas.

A few years ago there was a sharp spike in gas prices in my area because of the threat of a gas shortage. I believe prices spiked by about 25 cents a gallon in a couple days before they started to fall back again. As I was getting a fillup of 93 octaine in my 997S, I saw a gorgeous MB E46 AMG pull up to an adjacent pump. I had to smile when I saw the owner putting 87 octaine into his new $100K + MB, but I guess he liked saving the 40 cents a gallon. So he saved a little over $6 on the fillup. I wonder if it occured to him that he could have saved over $60K if he bought an A4 instead of the E46 AMG.