An organometallic compound added to unleaded gasoline to replace tetraethyl lead. It raises the anti-knock index, preventing premature detonation in the combustion chamber. Mechanics often spot its use by a distinct reddish-orange deposit left on spark plugs and oxygen sensors, which can eventually foul emission control systems if overused.
Look at the orange fouling on these spark plugs; this guy has been dumping methylcyclopentadienyl manganese tricarbonyl boosters in his tank.
Also heard as
- MMT
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.
Catalytic converter
An exhaust emission control device that reduces toxic gases and pollutants into less harmful compounds.