kauaiboy

ALOHA,

any of you filling up with Costco Supreme gas on your C300...i prefer Chevron or Shell Supreme but with Supreme price of $3.77 here in Kauai compare to $3.44 at Costco, sometimes it's very tempting to fill up.

LILBENZ230

Chevron gas is my gas of choice, as Techron additive seems to be the best there is. That said, octane ratings are standardized. If it's 91 or above, it's 91 or above. It may not have the detergents like Shell V-Power, Techron, or BP's Invigorate but it will not hurt your car.

C300Sport

When you say "the best" is that from marketing, Tier 1 participation or third party testing. I have to admit I have not tracked gas quality in the last few years...since I got a BP card with 5% back on thier gas. Anyhow, I know the Tier 1 suppliers are supposed to be good but not neccesarily the best or the only good ones with quality gas. Maybe Glyn or someone else can chyme in or send a link to where we can find some good, non biased info.

chokaay

From what I'm told, Costco gas is no different than any other gasoline. It all comes from the same refiner, and from the same terminal. (In fact, it's the same with all other gasoline "brands" as well.) The only difference is the additive package added in the gasoline when the tanker truck gets loaded at the terminal. Different "brands" have different additive packages. And different Costcos (and Shell/Cheveron/BP/76/Mobil/whatever stations) across the U.S. may have different "quality" gasoline from region to region, based on the refinery and terminal that services the region.

Costco buys gas from the "cheapest" source that day to fill its stations. Sometimes this can be from Chevron (and may come in a Chevron tanker truck). Other times it can be BP (and may come in a BP tanker truck). Other times from 76, Mobile, Shell, whatever. Rest assured you are getting the same quality gasoline as the other brands in your region... the only difference is the additive package (or lack thereof).

Whether the plausable lack of an extra additive package in your gasoline can harm your engine over time can be debated... but based on what I've read from some very knowledgeable forum members, the general consensus is that it MAY contribute to more engine build-up over time, but the fact of the matter is this has yet to be proven, and the extra additive packages in Cheveron or Shell or other gasolines are such a tiny part of the gasoline, it has yet to be proven that these additive packages make a significant difference in cleaning your engine (but they are certainly good for marketing).

If you want to remain on the absolute safe side, then stick to the "Tier 1" brands that MB recommends. However, in my experience I've filled up with Costco gas for a couple months after getting my car, then switched between Tier 1 brands and Costco, and I can say without a doubt that the Costco gas that I filled up with (always the same 2 stations) did make my car have slightly better gas mileage, and respond "better/stronger" when I stomped on the gas (no idea why, but perhaps the lack of an extra additive package helps?). Other Tier 1 brands seem to be "hit-and-miss" for me, but in general my car seems to like Shell 2nd best, and then all the others are pretty much the same with gas mileage and accelerator response. Other forum members report different preferences for their cars, so I think it's safe to say it really depends on the vehicle you drive, the gas stations you visit, and the region you live in.

As for engine build-up and harm, I think my car is too new to do a long-term study on the effects of different brands of gasoline vs. MB engine longevity, but who knows if sticking with any particular brand helps...

Peabody

I saw an article testing several common brands and measuring their power output on a dyno along with their fuel efficiency and Shell Power V came out tops in both categories. There's definitely a difference in brands, and the additives most certainly can make a difference. I can't find that article, but here's another independent evaluation that came to the same conclusion using a mounted engine.

Also, if you're using a chip tuning you definitely want to take advantage of the higher quality fuels.

mat2hu

the truth is ALL companies are forced to put additives such as "techron" for chevron and the v-power thing for shell. It's a federal requirement as far as i remember. The quality of the gas may be different but certainly not in any way that will harm your engine or help it live longer, because the stuff that in gas that cleans your engine is in every gas you purchase (it's mandatory for all gas companies to put it in their gas!) and from what i've experienced, shell may be considered better but i didn't like it, it made my throttle response much sharper and i felt like my car was slower because the RPM just kept bouncing up and down. I like arco the most because its cheaper and i love the way my car feels when i put arco gas in it: The car doesn't need to revv as high in order to reach the same speed.

If you're racing though that's another story. Use shell if u wanna race some1. lol

Sportstick

The link to the independent evaluation appears not to work. Can you tell us the URL or name of source, please?

imboom

In the Hawaii market there are two refineries. Chevron and Tesoro. The Chevron refinery does not deliver to any independent brands except for Chevron and Shell.

Costco receives their gasoline from a contract with Aloha Petroleum which in turn gets their gas from the Tesoro refinery. So if you wouldn't fill up at Aloha(many people wouldn't even though they advertise their "Tier 1" gasoline), then you may want to not fill up at Costco.

Peabody

Fixed link : http://www.motec.com.au/filedownload.php/fueltest.pdf?docid=2495

Sportstick

Costco was quoted on another web site with the following:

Costco Response to Top Tier Gasoline Inquiry Top Tier Gasoline

All gasoline retailers in a given market sell the same grade and quality fuel, as the government has very precise standards for octane and other gasoline characteristics. The only difference between different brands of fuel is the detergent additive package. Since 1995, the federal government requires that all gasoline sold in the U.S. contain detergent additives. These additives must be EPA-approved, and the government specifies the amount based on what it takes to keep engines free of deposits. Because it's a performance-based requirement, over the years the fuel suppliers have figured out ways to use less of these expensive additives to achieve the government standards. All Costco gasoline contains detergent additives in the amount necessary to meet these requirements.

Recently, several automakers (BMW, GM, Toyota, and Honda) announced their new "Top Tier" standard for gasoline, as they believe the government additive requirement is too low. They invited gasoline manufacturers to certify their fuel to this higher standard, and several have done so. Other major oil companies, such as BP, declined as they believe the auto manufacturers are simply trying to reduce their warranty claims. To achieve this voluntary "Top Tier" designation, all the fuel sold in the U.S. must meet the higher standard. Costco cannot currently do this as we buy from a variety of refiners and distributors around the country and do not own our own truck terminals where the additives are blended with the fuel.

Nor is it certain how much additive is really necessary to keep an engine clear of deposits. The fuel detergent is only one component, as anything that causes incomplete combustion will lead to valve deposits and fuel injector clogging. It's easy for an auto mechanic to simply declare the problem is the gasoline. So the science is uncertain, and the industry response is certainly not unanimous. Regardless, we are actively researching the issue directly with the various additive manufacturers. We are hesitant to raise the cost of fuel to our members without first understanding if this is simply a way for some brands to charge more for their fuel. We do know that we sell a tremendous amount of fuel with very few complaints.

Costco only buys fuel from reputable suppliers, and we do a very good job of maintaining our tanks and pump filters to assure clean fuel is delivered to our members. If you remain concerned about fuel deposits, Costco sells a four-pack of Chevron's Proguard fuel injector cleaner in our warehouses for about $10, or $2.50 per bottle. It's much less expensive to use a bottle of this occasionally than to buy higher priced fuel every time you fill up. Any auto parts store has a shelf full of similar products.

Again, all Costco fuel contains detergent additives sufficient to meet the government standards. As with anything we sell, our fuel is 100% guaranteed.

• http://www.toptiergas.com/

RobMaynard

Just for the sake of accuracy, this description of the Hawaii gasoline distribution system is outdated by some fifteen years of so. It may have been accurate in the mid-90's. Since then, Aloha has been an importer and currently buys from both Tesoro and Chevron. Shell gets its fuel from Tesoro.

So the comments regarding Costco are a bit more complicated than expressed in Imboom's message.

LILBENZ230

I admit to getting this from Glyn the oil man. His background makes him a really trustworthy source on this (and all things, really). Techron is the only one approved by Benz is what I was told.

E92-Lighting

dont use arco