Top Tier Detergent Gasoline
Top Tier Detergent Gasoline is a designation given by a consortium of major automakers — BMW, General Motors, Honda, Toyota, Mercedes-Benz,and Volkswagen/Audi — to gasoline brands in the U.S. and Canada that meet minimum specifications for maintaining engine cleanliness and performance and do not contain metallic additives. Top Tier gasoline contains higher levels of detergent additives in order to prevent the build-up of engine "gunk," which is known to reduce fuel economy and engine performance and possibly lead to mechanical breakdown. According to an automotive industry spokesman, the regular use of this type of gasoline results in improved engine life.
The Top Tier designation is separate from the issue of octane levels—in order to get the designation, gasoline companies must pass tests proving defined levels of engine-cleaning effectiveness in all grades of gasoline they sell, whether it is economy (low-octane) or premium (high-octane). However, premium gasolines may contain even higher levels of detergent additives. To date, more than 20 gasoline retailers in the US, and four in Canada, offer Top Tier gasoline.
Purpose of detergents in gasoline
Detergent additives serve to prevent the buildup of engine "gunk." Automotive journalist Craig Cole said, "Gasoline is an impure substance refined from a very impure base stock – crude oil. It’s an explosive hydrocarbon cocktail containing all kinds of different chemicals. In addition to its own molecular variability, refiners and retailers incorporate additional substances into the mix, from ethanol alcohol to octane enhancers."
While General Motors' fuels engineer Andrew Buczynsky says that no one has identified the exact molecule in gasoline that causes engine buildup, he says that consistent use of Top Tier detergent gasoline will keep engines cleaner. Engine "gunk" typically builds up in fuel injectors and intake valves, causing reduced fuel efficiency, acceleration, and power, as well as increasing emissions, rough idling, tendency to stall, and increased motor repairs. When fuel injectors accumulate deposits, they do not distribute fuel evenly, creating pockets of too much fuel and too little fuel. Too-little fuel around the spark plug dampens the combustion that drives the piston downward and may cause a misfire. When the frequency of misfires reaches a certain point, the on board computer turns on the "service engine" light on the dash. The repair for this type of problem depends on the severity of the deposits. In milder cases, a mechanic may solve the problem by simply scraping clean the fuel injectors, or by adding a can of fuel-injector cleaner into the gas tank. However, in some cases, the fuel injectors must be replaced. And if the deposits have formed on the intake valves, a more costly cylinder-head rebuild may be necessary.
Sulfur contamination of gasoline, which can contaminate fuel sending units and lead to erratic dashboard gauge readings, is another problem that higher levels of gasoline detergents can solve. It costs up to $1000 to repair this problem. Although one type of gasoline additive may resolve the problem of a sulphur-contaminated sending unit, the regular use of a Top Tier gasoline can prevent it from occurring in the first place.
Chris Martin at Honda says, 'we've supported it [Top Tier gasoline] because we've seen a benefit from it for our consumers in the long run.' . . . . 'We don't require that our vehicle owners use Top Tier gas' Martin said, but it helps 'make sure the engines are going to last as long as they could.'
Characteristics of Top Tier gasoline
In order to earn Top Tier certification, a gasoline must pass tests that demonstrate specified levels of: 1) deposit control on intake valves; 2) deposit control on fuel injectors; 3) deposit control on combustion chambers; 4) prevention of intake-valve sticking. Gasoline marketers agree when they sign on to Top Tier that all their grades of gasoline meet these standards. However, premium grade gasolines may have yet higher levels of detergent additives. Typically, Top Tier gasolines will contain two to three times the amount of detergent additives currently required by the EPA. The extra additives are estimated to cost less than a cent per gallon.
In addition to the detergent additive requirement, TOP TIER gasoline cannot contain metallic additives, because they can be harmful to a car's emissions-control systems.
According to its auto industry research and to automotive journalists, all vehicles will benefit from using Top Tier Detergent Gasoline over gasoline meeting the basic EPA standard. New vehicles will supposedly benefit by keeping their engine clean and running optimally, older vehicles may benefit with increased engine performance and prolonged vehicle life.
In the late 1980s, automakers became concerned with fuel additives as fuel injection technology became widely used in new cars. The injectors often became clogged, and the problem was found to be inadequate levels of detergent additives in some gasolines. The automakers began to recommend specific brands of gas with adequate content to their customers. But some gas companies were still not using detergents, and in a move supported by the auto industry, the federal government mandated specific levels of additives. The U.S. Environmental Protection Agency (EPA) introduced the minimum gasoline detergent standard in 1995.
However, the new regulations had an unexpected effect. The new EPA standards required lower levels of detergent additives than were then being used by a few major gasoline companies. When the new regulations came in, most gasoline marketers who had previously provided higher levels of detergents reduced the level of detergents in their gasolines to meet the new standard. The EPA detergent additive levels were designed to meet emissions standards but not engine longevity standards. Automakers said they were seeing persistent problems such as clogged fuel injectors, and contaminated combustion chambers, resulting in higher emissions and lower fuel economy.
By 2002, the automakers said their repair records suggested that the EPA standard for detergents wasn't high enough, but the EPA was not responsive when they asked them to increase the standards. These concerns were heightened by plans to introduce a new generation of vehicles that would meet the EPA’s “Tier Two” environmental standards for reduced emissions. These vehicles require higher levels of detergents to avoid reduced performance. Cars with direct injection technology (GDI) have been especially prone to carbon buildup, and car makers recommend fuels with higher detergent levels to combat the problem. At first GDI was mainly available in high-end autos, but it is now being used in mid-range cars and economy cars, such as the Hyundai Sonata, Ford Focus and Hyundai Accent.
In 2004 representatives of BMW, General Motors, Honda, and Toyota got together to specify what makes a good fuel. Using recommendations from the Worldwide Fuel Charter, a global committee of automakers and engine manufacturers, they established a proprietary standard for a class of gasoline called Top Tier Detergent Gasoline The new standard required increased levels of detergents, and restricted metallic content. Volkswagen/Audi joined the consortium in 2007. Gas brands can participate and get Top Tier listing if they meet certain standards, which includes performance tests for intake valve and combustion chamber deposits, fuel injector fouling, and intake valve sticking. Additive manufacturers pay for the testing, which costs an estimated $25,000 to $30,000, while gasoline companies pay an annual fee based on the number of stations it operates to participate in the program.
Most of the fuel experts and auto mechanics who have publicly commented on Top Tier gasoline recommend it. A 2007 USA Today article quoted three critics who say it has little or no benefit, but the same article quoted three endorsers of the new standard. Tom Magliozzi, co-host of NPR's weekly radio show, Car Talk, said that using top tier detergent gasoline is only critical on high-end vehicles. For other vehicles, he and another source said that periodic use of a concentrated engine cleaner every 100,000 miles will "often" clean out carbon buildup. However, journalist and automotive mechanics instructor Jim Kerr says that with some brands of gasoline, deposits can build up on intake valves in less than 10,000 kilometres (6200 miles). And General Motors fuels engineer Andrew Buczynsky says the various engine-cleaning additives available at auto-parts stores should be used with caution. He said some work but most don't, and that care must be taken when using these additives because some may contaminate the catalytic converter. Also, if too much is used, the additive may cling to valve stems and cause them to hang open.
Most mechanics agree that consistent use of a fuel with adequate cleaning ability is best. Magliozzi's co-host, Ray Magliozzi, said that in order to be sure of preventing buildup of fuel injectors and valves, motorists should use Top Tier gasoline "at least most of the time." Several others agree: Mechanic Pam Oakes says Top Tier gas is effective in cleaning carbon from engines and is worth buying. She says she’s seen the difference it can make and recommends it to all of her customers. Westside Autos in Clive, Iowa, and Motor Age columnist Larry Hammer also recommend Top Tier for removing carbon build-up, adding that a cleaner engine will also burn fuel more cleanly and therefore produce less emissions. Automotive mechanics instructor Jim Kerr concurs: "All gasoline is not created equal . . . Top Tier does have benefits."
In 2004 the standard was adopted by ten gasoline distributors. Chevron and QuikTrip were first, followed that same year by 76 Stations, Conoco, Phillips 66, Road Ranger, Kwik Trip, Shell, Entec Stations, and MFA Oil Company. Since then 20 more gasoline distributors have met the proprietary standard and Top Tier gasoline can now be found in gas stations all over the U.S. and Canada. In the U.S, Aloha Petroleum, ARCO, BP, Costco Wholesale, CountryMark, Express Convenience Centres, Exxon, Mobil, Hawaii Fuelling Network (HFN), Holiday Stationstores, Kwik Star, MFA Oil Break Time, Ohana Fuels, Schierl Oil, Superamerica, Texaco, and Tri-Par Oil Company, now offer Top Tier gasoline.
In Canada, Chevron Canada, Petro Canada, Shell Canada, Esso and most recently Tempo and the CO-OP brand (in selected regions), have attained the designation. In Puerto Rico, Puma Energy, Caribe LLC, and Shell offer Top Tier. Meeting this standard allows gasoline marketers to differentiate themselves from their competition. All stations selling the brand must meet Top Tier standards before the brand is qualified. They must pass separate tests measuring the ability of their gasolines to keep intake valves, combustion chambers, fuel injectors clean, and to prevent intake valves from sticking.
Although BP (British Petroleum) was identified in a media report as having detergent levels that met or exceeded Top Tier standards, the company did not initially elect to join the consortium. However, in June, 2013, the company decided to formally join Top Tier. The company explained that they had become aware that consumers increasingly seek out the TOP TIER designation, many by checking the Top Tier website to see which gasoline companies are listed.
A previous standard used was the BMW Unlimited Mileage Test. BP claims to meet this. BMW now mentions Top Tier gas in its owner's manuals but not the unlimited mileage test.
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