See the following (abbreviated to stay in post limit ) service bulletin from 2005:
Info - Fuel and Oil Additives - Facts and Myths/Maximizing Fuel Economy #05-00-89-072 - (Oct 24, 2005)
2006 and Prior All GM Cars and Trucks
2003-2006 HUMMER H2
2006 HUMMER H3
2005-2006 Saab 9-7X
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A Statement About Fuel Economy
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The information below contains reasonable and prudent advice for your dealership and the consumer to get the most from every gallon of gas.
The information below is presented in two easy to understand sections:
• What Not To Do: Engine and Fuel Additives, Alternate Fuels, and "Miracle" Products
• What to Do: Maximizing Fuel Economy/Minimizing Costs
WHAT NOT TO DO: Engine and Fuel Additives, Alternate Fuels, and "Miracle" Products
Various unproven products to improve vehicle fuel economy have been reported ranging from magnets that align molecules to chemical combustion improvers.
Most products claiming to provide benefits are based on unsubstantiated claims. Those that do present "scientific" results generally either have too little supporting data to be conclusive, have not conducted experiments in a controlled fashion, or cannot be substantiated by anyone else but the product's manufacturer.
The U.S. Federal Trade Commission summarizes results for products tested by the federal government at
www.ftc.gov/bcp/conline/pubs/autos/gasave.htm. A review of the list shows that the majority did not work, and for those that showed some effect, the benefit was too small to be cost effective.
Harmful Ideas That May Damage Your Vehicle and Increase Emissions
One more recent poor idea to improve fuel economy that should not be attempted is to blend either kerosene or diesel fuel into gasoline. Why? Both kerosene and diesel fuel are distillate fuels meant for use in compression ignition engines, not spark ignition engines. They have very low octane and since they are heavier (higher density) than gasoline, they will cause heavy engine deposits and degradation of engine oil.
Notice: Never put Kerosene or Diesel Fuel in your Gasoline Engine vehicle. This may result in inconsistent performance and permanent damage to your vehicle that is not covered by your New Vehicle Warranty.
Chemicals that are normally used as solvents also should not be used. These include acetone, ketones, and methanol. These solvents can be incompatible with your vehicles rubber or sealing components, and may dissolve the vehicle’s paint finish. In the case of methanol, corrosion of metal parts in the fuel system also may occur.
Notice: Never use acetone, ketones, or methanol additives in your vehicle. Some of these solvents may damage or corrode your fuel system. They are also very damaging to the painted surfaces of the vehicle if spilled.
WHAT TO DO: Maximizing Fuel Economy/Minimizing Costs
The best fuel economy possible is the direct result of proper maintenance and good driving habits. Listed below are GM's recommendations to achieve the best mileage possible. The first group are things to consider for your vehicle, while the second are tips relating to your driving habits.
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• Top Tier Fuels - Some fuel manufacturers provide gasoline advertised asTOP TIER DETERGENT GASOLINE (Chevron, Conoco, Phillips 66, Shell, Entec Stations, MFA , 76, Somerset Oil, QuikTrip, and Kwik Trip in the U.S. and Chevron in Canada. These fuels are preferable when and where available. They help to keep your fuel injectors and intake valves free of deposits. Clean engines provide optimal fuel economy, performance and reduced emissions. When Top Tier fuels are not available, consider a bottle of GM Fuel System treatment PLUS, P/N# 88861011 (in Canada, #88861012), at oil change time which will remove intake system and injector deposits. GM does not recommend any other fuel system cleaner.
Important: DO NOT confuse Top Tier Fuels with Higher Octane (Plus/Premium Grade Fuel) commonly sold at most all gas stations. Plus and Premium fuels are required in some high performance GM vehicles. However, they do not necessarily represent higher detergency present in TOP TIER Detergent Gasoline.
Important: For additional information regarding Top Tier fuels and availability, please refer to Corporate Bulletin Number 04-06-04-047E for U.S. or 05-06-04-022 for Canada.
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