Oilslick

Even among Decepticon scientists, Oilslick is considered unethical. He's been known to test new inventions on his own faction if no one's looking, and one of his specialties is Cosmic Rust.

Timeless
Oilslick was probably behind a number of incidents of Cosmic Rust being tested on Decepticons, including the destruction of Outpost Thetarus. Barricade opted to blame the attacks on Fisitron instead and hunted the Autobot down.

Swindle's Spiel
Swindle, Swindle and Swindle counted a couple of Oil Slicks among their best customers.