This oxygenate additive blends with gasoline to raise its octane number and help the fuel burn more completely. Refiners historically used it to replace lead and prevent premature detonation in high-compression engines. Environmental concerns over groundwater contamination have led to its phase-out in many regions, where it is typically replaced by ethanol.
The soil test came back positive for methyl tert-butyl ether, so that old storage tank definitely leaked before the switch to ethanol.
Mechanics and engineers almost exclusively refer to this chemical by its acronym, MTBE. Stale gas in a long-abandoned vehicle might still contain it, recognizable by a sharp, turpentine-like odor distinct from ethanol blends.
Also heard as
- MTBE
- methyl t-butyl ether
Related terms
Anti-knock index
The standard numerical rating of a fuel's resistance to premature ignition.
Knock
An abnormal and damaging combustion event where the air-fuel mixture self-ignites prematurely.
Detonation
An uncontrolled secondary explosion in the combustion chamber that causes severe engine damage.
E10
A motor fuel blend consisting of 10 percent ethanol and 90 percent gasoline.