The Importance of Fuel Additives

Many professional auto repair technicians often classify fuel additives as solutions to various fuel delivery problems, but fuel additives can prevent or remedy many fuel delivery system problems. Most of these fuel additives will fall into seven basic categories:

Gasoline Stabilizers

Loss of a gasoline’s volatility isn’t a factor in normal driving, but it becomes a major problem when starting seasonal-use vehicles like boats, motor homes, lawn care equipment and electric generators. Using a gasoline stabilizer basically reduces hard-starting caused by the tendency of the more gaseous components of gasoline to evaporate into the atmosphere. Many new formulas now include corrosion inhibitors that prevent fuel system corrosion from gasolines.

Octane Boosters

Ethyl lead was used in gasoline for many years to increase the gasoline’s octane rating and lubricate engine valve seats. After the use of ethyl lead was discontinued during the 1970s, octane booster additives became popular for increasing the octane rating of gasoline used in the high-compression engines of the day. In most cases, a valve seat lubricant is included in an octane booster to reduce wear on antique and collector car engines equipped with cast-iron valve seats.

Fuel Injector Cleaners

The symptoms of clogged fuel injectors are hard-starting, poor cold-engine performance and sluggish acceleration. These symptoms are caused by carbon deposits clogging the fuel injector nozzles. Most lower-priced fuel injector cleaners are designed as preventive maintenance additives while the higher-priced cleaners are designed to also remove heavy carbon deposits from cylinder heads, valves and pistons. Any of these additives generally perform well when used as directed.

Upper Cylinder Lubricants

Thanks to the use of high-viscosity engine oils, varnish deposits and low-speed driving, early L-head or “flat head” gasoline engines often had problems with engine valves sticking in their valve guides. Light-viscosity, high-detergent upper cylinder oils were designed to be added to the fuel tank to help clean and lubricate sticking valves. Nowadays, sticking valves are rare and usually caused by insufficient oil clearance in the valve guide assembly. Nevertheless, many modern gasoline additives contain some type of upper cylinder lubricant to lubricate valve guides, seats and piston rings.