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.<ul><li><a href="http://www.toptiergas.com/">http://www.toptiergas.com/</a</li></ul>

I wonder how they can guarantee their fuel? "I'd like to return fuel I purchased, please siphon it o
 

out of my tank. Kthxbye"

Anyway I usually gas up at Costco and have had no problems with their gas.

I was told by a Costco employee that they purchase gas from Union 76.
 

It works all right for most cars. However, my B5 S4 w/ MTM chip did not like the Costco premium gas at all - lots of pinging under load. However, when the car was unchipped, the Costco premium worked fine.

Odd. A local tuner tested various premium gasolines in his chipped S4..
 

...and recommended Union 76, saying it "threw the least codes". So, dunno if Costco is really using Union 76? (at least not in the Bay Area).

I gave up my S4 in 2004. Maybe the quality has improved?

Dated Information on Costco Wholesale
 

This thread is now very dated, as Costco Wholesale embarked on a program to blend their additive package at each Warehouse location serving up fuel. This permits meeting the higher standards, and delivering a consistent fuel mix across all markets where the equipment has been installed.

Holy thread necro.... Yeah the information is old, the posts are 4 years old!