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What is 'Top Tier' Gas And Why Should You Use It?

Published Sep 12th 2007, 5:00pm by Jody DeVere in Featured Articles

Where do you buy your gas? Do you have loyalties based on location, cost, or brand? Do you choose to purchase your fuel with any thought to how its additives can help to keep your engine clean? I recently attended a presentation at the Phoenix Automotive Press Association, given by Jens Mueller-Belau of Shell Oil. It was fascinating. We ate pasta and learned about dreaded engine "gunk," and how gasoline detergents can help clean the gooey carbon deposits left behind as part of the engine's fuel combustion process.

A while back, six of the world's top automakers (BMW, General Motors, Honda, Toyota, Volkswagen and Audi) determined that current EPA minimum detergent requirements don't go far enough to ensure optimal engine performance. Even though minimum additive performance standards were first established by EPA in 1995, many gasoline brands have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. So they established the concept of endorsing specific companies that provide Top-Tier fuels to ensure optimal performance in their vehicles.

Currently, many gasoline retailers provide fuels with lower-quality additive packages that can build up deposits on fuel injectors and intake valves. Others can build up deposits in combustion chambers and may lead to intake valve sticking. These lower levels of additives might meet the minimums required by the EPA, but they can still have negative impacts on engine performance and vehicle responsiveness. That's the "gunk" you may have heard about in fuel advertisements.

That might sound like a lot of technical mumbo jumbo, but in a nutshell, these six specific vehicle manufacturers are saying that if drivers want their high-performance cars to function at their best, then they must feed them Top-Tier fuels designed to provide optimum performance and keep their engines clean.

Enginegunk Don't be confused; I'm not talking about octane. Some high-performance vehicles do require fuels with higher octane levels and these can be purchased at any gas station; Top-Tier fuels offer additional detergent additives meant to reduce carbon deposits on fuel injectors and intake valves and only certain retailers certified as Top Tier. These cleansing additives are present across all octane levels and can benefit the performance of any car by reducing gunky buildup that may have been left behind after using cheaper fuels. Check out the photo from a study done by Shell that shows the difference in the amount of deposits left by standard, low-additive-content fuels, as compared to the cleaner valves that burned Shell gasoline. (Be sure to click on it to see the detail of the gunk!) These gooey deposits formed after only 5000 miles of driving with low-cost, low-additive-content gasoline. Yuck!

Gasoline retailers must meet the high Top-Tier standards with all grades of gasoline in order to be approved by the automakers as providing Top Tier Detergent Gasolines. Currently, the following retailers offer high-detergent fuels that are certified to meet the requirements of BMW, General Motors, Honda, Toyota, Volkswagen and Audi: QuikTrip, Chevron, Conoco, Phillips, 76, Shell, Entec Stations, MFA Oil Company, Kwik Trip/Kwik Star, The Somerset Refinery, Inc., Chevron-Canada, Aloha Petroleum, Tri-Par Oil Company, Shell-Canada, Texaco, Petro-Canada, and Sunoco-Canada.

More information can be found at You can also learn more by taking a fun and educational quiz offered by Shell's own spokesman, Dr. Fuelgood.

By Brandy Schaffels
Contributing Editor

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