Gasoline additives increase gasoline's octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhibitors, oxygenates and antioxidants.
Some additives are harmful and are regulated or banned in some countries.
Oxygenates
Alcohols:
Methanol (MeOH)
Ethanol (EtOH)
Isopropyl alcohol (IPA)
n-butanol (BuOH)
Gasoline grade t-butanol (GTBA)
Ethers:
Methyl tert-butyl ether (MTBE), now outlawed in many states of the U.S. for road use, mostly because of water contamination.
Tertiary amyl methyl ether (TAME)
Tertiary hexyl methyl ether (THEME)
Ethyl tertiary butyl ether (ETBE)
Tertiary amyl ethyl ether (TAEE)
Diisopropyl ether (DIPE)
Antioxidants, stabilizers
Butylated hydroxytoluene (BHT)
2,4-Dimethyl-6-tert-butylphenol
2,6-Di-tert-butylphenol (2,6-DTBP)
p-Phenylenediamine
Ethylenediamine
Antiknock agents
Tetraethyllead, now banned almost everywhere for causing brain damage.
Methylcyclopentadienyl manganese tricarbonyl (MMT) is an extremely poisonous neurotoxic substance and is fatal if swallowed/inhaled and will cause a disease similar to Parkinson's called manganism.
Ferrocene highly toxic
Toluene
Isooctane
Triptane
Lead scavengers (for leaded gasoline)
Tricresyl phosphate (TCP) (also an AW additive and EP additive)
1,2-Dibromoethane
1,2-Dichloroethane
Fuel dyes, most common:
Solvent Red 24
Solvent Red 26
Solvent Yellow 124
Solvent Blue 35
Fuel additives in general
Ether and other flammable hydrocarbons have been used extensively as starting fluid for many difficult-to-start engines, especially diesel engines
Nitromethane, or "nitro," is a high-performance racing fuel
Acetone is a vaporization additive, mainly used with methanol racing fuel to improve vaporisation at start up
Butyl rubber (as polyisobutylene succinimide, detergent to prevent fouling of diesel fuel injectors)
Picrate improves combustion, increases fuel mileage
Nitromethane can increase the cetane number of diesel fuel, improving its combustion properties
Nitrous oxide, or simply nitrous, is an oxidizer used in auto racing
Fuel additives in the United States are regulated under section 211 of the Clean Air Act (as amended in January 1995). The Environmental Protection Agency (EPA) requires the registration of all fuel additives which are commercially distributed for use in highway motor vehicles in the United States, and may require testing and ban harmful additives. The EPA also regularly reviews the health and net economic benefits of Clean Air Act policies.
The act also requires deposit control additives (DCAs) be added to all gasolines. This type of additive is a detergent additive that acts as a cleansing agent in small passages in the carburetor or fuel injectors. This in turn serves to ensure a consistent air and fuel mixture that will contribute to better gas mileage.
