You may not realize it, but not all gasoline is created equal.
Some brands meet higher standards than those set by the U.S. government. They use higher-quality additives that keep engines cleaner. Lower-quality gas uses lower-quality additive packages that can build up deposits on fuel injectors and intake valves. As you might imagine, those buildups can lead to poor engine performance.
Brief History of Gas Additive Standards
Gasoline additives date way back to the early 1900s when they were first used to help prevent knocking, which could damage the engine.
In 1921, automotive engineers working for General Motors discovered that tetraethyl lead (better known as lead) provided octane to gasoline and reduced engine knock. While aromatic hydrocarbons (such as benzene) and alcohols (such as ethanol) were also known octane providers at the time, lead was the preferred choice due because it was cheaper to make. However, it was also proven a serious health hazard.
Deposit control additives were first added to gasoline in the 1970s to prevent carbon deposit formation on the intake valves. Congress also passed the Clean Air Act in 1970. The government then started to phase out lead gasoline due to its proven harmful health effects.
In the 1980s, new electronic fuel injection systems caused another problem. Automakers discovered the fuel injectors could become stuck or clogged due to contamination in the base fuel. The gasoline industry responded with an aggressive detergent additive package that removed fuel injector and intake valve deposits, but ultimately resulted in excessive combustion chamber deposits. The deposits became so bad on some engines that the carbon build up resulted in mechanical interference between the pistons, valves, and cylinder heads which resulted in engine failures. The automotive and fuel industry responded again with different detergent chemistry compositions that limited deposit build up.
In 1996, the Environmental Protection Agency established a base standard that specified the lowest additive concentration permissible for detergent additives used in gasoline sold in the United States. Those standards are in place today.
While the EPA’s base standard helped minimize certain deposits, some automakers felt it did not go far enough in reducing intake valve deposits. So in 2004, a group of vehicle manufacturers created the TOP TIER Detergent Gasoline program to develop a higher standard.
Top Tier Brands List
In a 2016 American Automobile Association study, engines running on TOP TIER gasoline averaged 19 times fewer intake valve deposits than when it was operated on non-TOP TIER gasoline. You can read more about the study here.