History of Lead Additives in Gasoline

Prior to the mid 1970’s automotive engines were built with non-hardened valve seats that were protected from a condition know as valve-seat regression by the addition of Tetraethyllead to the gasoline supply in the U.S.  Tetraethyllead provided a lubricating cushion between the valves and valve seats that greatly reduced the problem of valve-seat regression and also increased the octane level of the gasoline reducing pre-ignition, also known as “engine knock.”

It’s important to understand how valve-seat regression occurs in the absence of a lead additive  gasoline.  High displacement, high compression engines generate high internal temperatures that expose internal engine parts to potential damage.  In the case of the valve train, when valves that close down on overheated valve seats the two components can become momentarily fused together.  This is called “microwelding.”  When the valves then open the micro weld tears apart and as this continues over time the valve will no longer seat correctly resulting in valve-seat regression.  This leads to compression and power loss and contributes to pre-ignition, all of which can result in severe engine damage.

When it became known that lead was detrimental to people’s health, the environment and automotive catalytic converters in the 1970’s, lead additives were phased out of the U.S. gasoline supply.  As a result of the elimination of lead in gasoline  manufacturers began to design and produce hardened valve seats that were resistant to microwelding and regression.

So do you need to use a lead substitute in your gasoline?

If your classic car engine has been rebuilt in the last 25 years it’s likely that hardened valve seats were used and a lead substitute isn’t needed.

On the other hand, if the engine is original and uses non-hardened stock valve seats a lead substitute is recommended, especially if you operate it under high rpm conditions. Using a lead substitute additive can offer peace of mind that you are doing what you can to protect your investment.

Dominator Octane Boost contains MMT (Methylcyclopentadienyl) manganese tricarbonyl) which is a metal additive that provides a lubricating barrier between valves and valve seats. 

It also boosts octane levels up to four numbers which is beneficial to older high-compression enginesIt also boosts power and response in all types of four and two-stroke engines that run on gasoline.  After one treatment you’ll notice an improvement in engine response and a reduction or elimination of any engine knock that may be present.