Tetraethyllead Antiknock Agent
Tetraethyllead, or TEL for short, (named in-game as tetraethyllead antiknock agent) is an additive that improves the performance of fuels.
Production

TEL is made in a Chemical Plant:

Uses
It is currently used to dope 3 fuels: Gasoline, Coal Gasoline and Petroil.
It improves the performance of the fuels, especially for coal gasoline.Any of them can be mixed in either an industrial mixer or a chemical plant, where 10000 mB of fuel with TEL give 12000 mB of the leaded fuel.
Below is a chart with the performance difference between the three fuels and their leaded counterparts:
Petroil: 195 kHE per bucket | 130 kTU per bucket ----> Leaded Petroil: 293 kHE per bucket | 195 kTU per bucket
Gasoline: 1.51 MHE per bucket | 605 kTU per bucket ----> Leaded Gasoline: 2.26 MHE per bucket | 907 kTU per bucket
Coal Gasoline: 9.52 MHE per bucket | 6.35 MTU per bucket ----> Leaded Coal Gasoline: 14.2 MHE per bucket | 9.52 MTU per bucket
This improvement isn't without its burden: When burning the fuel, besides adding soot pollution into the environment, it will also add heavy metal pollution into the environment, which makes glyphids stronger and increases mob health.