Logo of Top Tier Detergent GasolineLogo of Top Tier Diesel Fuel
Top Tier Detergent Gasoline and Top Tier Diesel Fuel are performance specifications and trademarks designed and supported by several automakers.[1]BMW, General Motors, Fiat Chrysler Automobiles, Ford, Acura/Honda, Toyota, Volkswagen, Mercedes-Benz, Navistar, Audi, and Volvo support the gasoline standard, while General Motors, Volkswagen, Detroit Diesel, and Navistar support the diesel standard (as of 2018[update]). Top Tier fuels must maintain levels of detergent additives that are believed to result in a higher standard of engine cleanliness and performance as compared to the United States Environmental Protection Agency (EPA) requirement. In addition, Top Tier fuels may not contain metallic additives, which can harm the vehicle emission system and create pollutants. As of 2018, Top Tier Detergent Gasoline is available from 61 licensed retail brands, and Top Tier Diesel Fuel is available from 5 licensed retail brands.
Licensed Top Tier fuel retailers use a higher level of detergent additive which can increase fuel economy and optimal engine performance. According to an automotive industry spokesman, the regular use of this type of gasoline results in improved engine life.[2]
The Top Tier standards must apply to all grades of gasoline or diesel that a company sells, whether it is economy (low-octane) or premium (high-octane).[3]
Purpose of detergents in gasoline
Detergent additives serve to prevent the buildup of engine "gunk," which can cause a host of mechanical problems. Automotive journalist Craig Cole writes, "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."[4]
While General Motors' fuels engineer Andrew Buczynsky claims that no one has identified the exact molecule in gasoline that causes engine buildup, he suggests using Top Tier Detergent Gasoline to keep one's engine cleaner.[5] Engine gunk typically builds up in fuel injectors and on intake valves, and if severe can result in reduced fuel efficiency, acceleration, and power. Left unchecked, engine gunk can also contribute to increased emissions, rough idling, and tendency to stall, and can therefore increase required motor repairs.[6][7] 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 adding a can of fuel-injector cleaner into the gas tank. However, in some cases, the fuel injectors must be replaced. Deposits formed on the intake valves may be removed via walnut shell blasting. In severe cases, a more costly cylinder-head rebuild may be necessary.[5]
Certain forms of sulfur that refiners or pipelines may leave in finished gasoline, such as mercaptans and hydrogen sulfide, can contaminate fuel sending units and lead to erratic dashboard fuel gauge readings, which may be expensive to repair. However, this problem has become less common since 2006, since manufacturers have been making these units with improved alloys that are less affected by these forms of sulfur.[8]
Chris Martin at Honda states, "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 [but it helps] make sure the engines are going to last as long as they could."[9]
Characteristics of Top Tier gasoline
In order to be certified as Top Tier, a gasoline must pass a series of performance 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.[4] Gasoline marketers agree when they sign on to Top Tier program that all their grades of gasoline meet these standards.[10] However, premium grade gasoline may have yet higher levels of detergent additives.[11] Typically, Top Tier gasoline will contain two to three times the amount of detergent additives currently required by the EPA.[12] The extra additives are estimated to cost less than a cent per gallon.[13]
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.[4]
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.[10][3][14] New vehicles will supposedly benefit by keeping their engine clean and running optimally, while older vehicles may benefit with increased engine performance and prolonged vehicle life.
History
In the late 1980s, automakers became concerned with fuel additives as more advanced 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 gasoline. The automakers began to recommend specific brands of gas with adequate content to their customers. But some fuel marketers 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[15] in 1995.
However, the new regulations had unintended consequences. The new EPA standards required lower levels of detergent additives than were then being used by a few major fuel marketers. 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.[16] 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.[17]
By 2002, the automakers said their repair records suggested that the EPA standard for detergents was not 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.[16] Cars with gasoline direct injection (GDI) have been especially prone to carbon buildup, and car makers recommend fuels with higher detergent levels to combat the problem.[18] 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.[19][20][21]
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 GasolineThe new standard required increased levels of detergents, and restricted metallic content. Volkswagen/Audi joined the group of automakers in 2007. Gas brands can participate and get a TOP TIER license 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, the cost of which varies from year to year, while gasoline companies pay an annual fee based on the number of stations it operates to participate in the program.[22]
In addition to higher detergent levels, Top Tier standards also require that gasoline be free of metallic additives, which can be harmful to the emissions control systems in cars.[3][23]
In October 2017 a Top Tier Diesel Fuel program was launched.[24]
Reception
Most of the fuel experts and auto mechanics who have publicly commented on Top Tier gasoline recommend it[citation needed]. 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.[11]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.[25] 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 kilometers (6200 miles).[7] 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 do not, 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.[5]
Most mechanics agree that consistent use of a fuel with adequate cleaning ability is best[citation needed]. 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."[25][26] 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.[27] 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.[28] Automotive mechanics instructor Jim Kerr concurs: "All gasoline is not created equal . . . Top Tier does have benefits."[10]
Availability
In 2004 the standard was adopted by ten gasoline distributors. Chevron and QuikTrip were first,[29] followed that same year by 76 Stations, Conoco, Phillips 66, Road Ranger, Kwik Trip/Kwik Star, Shell, and MFA Oil Company. Since then, many 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.[30][31]
Top Tier is also available from select brands in Canada, El Salvador, Guatemala, Honduras, Mexico, Panama, and Puerto Rico. 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 gasoline to keep intake valves, combustion chambers, fuel injectors clean, and to prevent intake valves from sticking.[32]
Top Tier licensed retail brands
As of April 2022, there are two Top Tier Diesel brands[33] and more than 60 Top Tier gasoline brands[32] in the US and Canada.
In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. The exhaust gas displaces atmospheric air and reduces O2 in the combustion chamber. Reducing the amount of oxygen reduces the amount of fuel that can burn in the cylinder thereby reducing peak in-cylinder temperatures. The actual amount of recirculated exhaust gas varies with the engine operating parameters.
A four-strokeengine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum in the cylinder through its downward motion.
Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. the compressed air-fuel mixture is ignited by a spark plug or by heat generated by high compression, forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust port.
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, detergents, dispersants, and, for multi-grade oils, viscosity index improvers. The main function of motor oil is to reduce friction and wear on moving parts and to clean the engine from sludge and varnish (detergents). It also neutralizes acids that originate from fuel and from oxidation of the lubricant (detergents), improves the sealing of piston rings, and cools the engine by carrying heat away from moving parts.
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous energy profile. Non-transportation applications, such as industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process.
Vehicle emissions control is the study of reducing the emissions produced by motor vehicles, especially internal combustion engines. The primary emissions studied include hydrocarbons, volatile organic compounds, carbon monoxide, carbon dioxide, nitrogen oxides, particulate matter, and sulfur oxides. Starting in the 1950s and 1960s, various regulatory agencies were formed with a primary focus on studying the vehicle emissions and their effects on human health and the environment. As the worlds understanding of vehicle emissions improved, so did the devices used to mitigate their impacts. The regulatory requirements of the Clean Air Act, which was amended many times, greatly restricted acceptable vehicle emissions. With the restrictions, vehicles started being designed more efficiently by utilizing various emission control systems and devices which became more common in vehicles over time.
Emission standards are the legal requirements governing air pollutants released into the atmosphere. Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources over specific timeframes. They are generally designed to achieve air quality standards and to protect human life. Different regions and countries have different standards for vehicle emissions.
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.
Gasoline direct injection (GDI), also known as petrol direct injection (PDI), is a mixture formation system for internal combustion engines that run on gasoline (petrol), where fuel is injected into the combustion chamber. This is distinct from manifold injection systems, which inject fuel into the intake manifold.
Manifold vacuum, or engine vacuum in a petrol engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.
Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction produces heat that can be transformed into work in a heat engine.
A crankcase ventilation system (CVS) removes unwanted gases from the crankcase of an internal combustion engine. The system usually consists of a tube, a one-way valve and a vacuum source.
Fuel-saving devices are sold on the aftermarket with claims they may improve the fuel economy, the exhaust emissions, or optimize ignition, air flow, or fuel flow of automobiles in some way. An early example of such a device sold with difficult-to-justify claims is the 200 mpg‑US (1.2 L/100 km) carburetor designed by Canadian inventor Charles Nelson Pogue.
A throttle is a mechanism by which fluid flow is managed by constriction or obstruction.
Fuel Freedom International is a multi-level marketing company based in Altamonte Springs, Florida and co-owned by Wendy Lewis and Randy Ray. It sells pills trademarked as MPG-CAPS, which are claimed to improve fuel economy, reduce emissions and increase engine power when used as a gasoline additive.
United States vehicle emission standards are set through a combination of legislative mandates enacted by Congress through Clean Air Act (CAA) amendments from 1970 onwards, and executive regulations managed nationally by the Environmental Protection Agency (EPA), and more recently along with the National Highway Traffic Safety Administration (NHTSA). These standards cover tailpipe pollution, including carbon monoxide, nitrogen oxides, and particulate emissions, and newer versions have incorporated fuel economy standards. However they lag behind European emission standards, which limit air pollution from brakes and tires.
Bi-fuel vehicles are vehicles with multifuel engines capable of running on two fuels. The two fuels are stored in separate tanks and the engine runs on one fuel at a time. On internal combustion engines, a bi-fuel engine typically burns gasoline and a volatile alternate fuel such as natural gas (CNG), LPG, or hydrogen. Bi-fuel vehicles switch between gasoline and the other fuel, manually or automatically. A related concept is the dual-fuel vehicle which must burn both fuels in combination. Diesel engines converted to use gaseous fuels fall into this class due to the different ignition system.
N-Methylaniline (NMA) is an aniline derivative. It is an organic compound with the chemical formula C6H5NH(CH3). The substance is a colorless viscous liquid, Samples turn brown when exposed to air. The chemical is insoluble in water. It is used as a latent and coupling solvent and is also used as an intermediate for dyes, agrochemicals and other organic products manufacturing. NMA is toxic and exposure can cause damage to the central nervous system and can also cause liver and kidney failure.
The Cummins X-series engine is an Inline (Straight)-6 diesel engine produced by Cummins for heavy duty trucks and motorcoaches, replacing the N14 in 2001 when emissions regulations passed by the EPA made the engine obsolete. Originally called the "Signature" series engine, the ISX uses the "Intellect System" to further improve the engine. This engine is widely used in on highway and vocational trucks and is available in power ranging from 430 hp all the way to 620 hp 2050 lb-ft. The QSX is the off-highway version of the ISX with the Q standing for Quantum. The QSX is used for industrial, marine, oil & gas and other off-highway applications. Cummins also produced a 650 hp and 1950 lb-ft version for the RV market.
An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance. This process transforms chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.
↑ Cole, Craig. "Which Gas Stations Sell the Best Quality Gasoline?". www.autoguide.com. Chris Martin, a spokesman for Honda said '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.'
1 2 Steve Everly (August 1, 2004). "Automakers, Oil Industry in Fuel Fight". Kansas City Star.
↑ Larry Hemmer (2008). "The Quest for Better Fuel Economy". Motor Age. p.72. The industry has encountered an increased level of intake valve, fuel injector and combustion chamber contamination problems. These deposits have a direct effect on the engine performance resulting in . . . poor fuel economy and high emissions output. This has prompted BMW, GM, Honda and Toyota to adopt a new class of fuel called Top Tier fuel.
↑ Pete Meier (August 2012). "Some Do, Some Don't: What Factors Cause Carbon Buildup in GDI Engines?". Motor Age. pp.30–35.
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