Wayne O

You bought a high performance Corvette....I suggest you use the recommended fuel its designed to run best on.

Daekwan06

Agreed on all accounts. Shell VPower for me.

2vette2

I think the OP was just asking a question. It does not seem to me that he was being "cheap". If you do not know something, what is wrong with asking the question? The manual is not a best seller and what else is this forum for if not to help each other?

jackhall99

Nobody has posted that.

Carver Electrics

Carver Electrics

TLS_Addict

I dump some whisky in my tank every 3k miles.

SanDiegoBert

If I'm going on a road trip, San Diego to Monterey or Vegas, I gas up with regular. Don't need the octane when cruising steady at 75 MPH for hours.

However, in the mountains, or on a club run, I use 91, the highest octane regularly available at the pump (in San Diego).

The MPG difference is hard to compare, since I would need to do the same trips using different octanes. But the car gets fabulous mileage with anything from 87 to 91 octane, so I'm satisfied.

NeverAgain

Out here in Colorado, they brew the gas with 85 (regular) and 91 (premium) octane. Higher octane like the other parts of the country (87 and 93) is not needed due to the high altitude is the common answer. Gas should be cheaper here since we don’t get the higher octane but it’s not that way of course. I use 91 out here. Also, watched one of those 20/20 type shows years ago addressing gas brand loyalty. Seems that gas is “fungible” and what is taken out at the receiving end has to be replaced at the sending end. In other words, in theory all the stations get their gas from the same source. Now if the truck filling up the station storage tanks is a corporate truck, then those shipments may have been treated/enhanced with those corporations’ special additives. Most of the time I see a generic truck filling up the station tanks…

SanDiegoBert

My observations, as well.

dvilin

06 C6 vert

Use premium only, the Vette will pull timing with regular and neuter the car.

The Vette can "Hear" knocking that we cant and pulls timing. The regular knocks very easy.

owebo

I do the same thing....I am always putting 87 in mine...can't tell the difference unless I have to put E-10 in it, that stuff suks.......

Vinnie T

As far as the OP's question, use premium fuel since that is what is desingated for the motor in the car and you might as well get the advantages from it in performance. I tend to use Shell or Chevron.

Not to change the subject, but is this whole "top tier" thing a reality or a marketing gimmick for the oil companies? Do they have to pay a fee to get on the list or to be recommended by a manufacturer?
Case in point: I'm going to take a wild guess that no one here would rate the fuel that Costco dispenses as "top tier", right? Yet, a couple weeks ago, I'm leaving Costco and following the tanker truck that just dropped fuel at Costco. It's next stop is about a mile away at a 76 station, a fuel that is listed as "top tier". I would say that the tanker doesn't have two different blends on board, so it appears that the Costco station was receiving the same fuel as the "top tier" 76 station. What gives????

LDB

Top tier charges small fees to cover the cost of administering the program. It was started by car companies, not oil companies. GM was among the leaders. Their objective was to reduce their warranty costs by encouraging cleaner fuels in the marketplace. To be top tier, you must pass actual engine tests where engines are run for extended periods under controlled conditions, then are disassembled and checked for precise quantity of deposits in critical areas. While it is not true to say that gas is lousy if it isn’t top tier, it is true to say that if you buy top tier, you are guaranteed of getting gas with highest possible engine cleanliness that has been demonstrated by actual engine testing.

As far as the delivery truck going from Costco to a Union76 station, that sometimes does happen, but you can’t rely on it. A retailer that advertises top tier, or one that advertises a specific additive package like Chevron Techron or nitrogen enriched Shell must provide that type of gas every single time without fail. Penalties for failing to do so are too high to risk anything else. Independents like Costco get gas from wherever is most convenient and/or cheapest. Sometimes it happens that at some particular time at some particular station, it’s cheapest or most convenient to have to have somebody with a load of gas with additives for Shell or Chevron or Union76 drop off a delivery at Costco. There is no law against giving a customer more than he paid for. But you can’t rely on it. Next week, that same Costco may get a load from a generic supplier with generic additives. Again, remember that generic gas is not guaranteed bad, it is just that it is not guaranteed to have an additive package that has demonstrated top tier cleanliness.

Vinnie T

Thanks for the rundown on top tier. This particular company (Interstate Oil) is based here in central CA and seems to service a lot of the area regardless of brand. I'm pretty sure that they are a fuel delivery company as opposed to a refiner. Sometimes I see "company" trucks at Chevron, Shell, etc. that are branded as such, and sometimes I see these independents making the delveries. CA has always had strict rules on fuel cleanliness and additives ever since FI came into vogue, so maybe the packages aren't that much different between companies at this point. Or mayb e the regular fuels are similar as opposed to the premium blends so they can service more stations and brands.

SanDiegoBert

I've been buying gas at Costco for over 10 years for all of my vehicles, practically exclusively . . . Even when I travel. Never had a gas-related problem.

Sometimes I wonder about this "top-tier" thing . . . Is it a hoax or just a marketing ploy?

Gearhead Jim

As others said, the car will normally run ok on regular; the system will reduce spark advance when it detects knock from low octance. You will get slightly lower acceleration and fuel economy.

Also, using regular gas means you are betting your engine that the knock sensors and ECM will do their job properly. That's a bet I don't want to make.

Finally, the Top Tier gas (google it to get the list of companies) has a better additive package to keep the internals of your engine cleaner. Occasional use of non Top Tier won't hurt anything, but over the long run you end up with more deposits.

Gearhead Jim

The cost for Top Tier certification tests on your gasoline are a tiny fraction of what the additives will cost when you start selling the stuff. I can't find any reason why a gasoline company wouldn't do the Top Tier certification, except they don't want to buy the better additives to actually put in the gas they sell.

LDB

I absolutely did not say that Costco or any other “generic” gas had problems. All gas must meet minimum EPA standards for additives. However, those standards are based on additive concentrations, not on actual engine testing. That’s why GM and other car companies came up with top tier. There are several different “flavors” of additives. Going top tier makes them prove their effectiveness with actual engine tests, not just additive concentrations. You can rely on the fact that if you tore down engines after 50000 miles, those running top tier would be cleaner than those running generic. For about the zillionth time, that doesn’t mean engines that ran generic gas would be dirty. It means just what it says. Top tier engines would be cleaner. As far as branding on the delivery trucks, most delivery is done by independent delivery companies, not the oil companies themselves. But their contracts are such that if they are delivering to Chevron, you can be sure they are adding Techron, and if to Shell, they have the nitrogen enriched package, etc. As stated earlier, sometimes you get top tier at a non-branded station, but you never get gas that isn’t top tier at a top tier station.