Synth oil

Synth oil is a circulatory fluid found in Combine synths, most commonly Striders or Hunters. It is sought after by Benefactor cultists who often use it in communion rituals.

Properties
Synth oil is a psychoactive substance. Upon consumption, it induces vivid audiovisual and tactile hallucinations in the user. During these hallucinations, users typically feel intense feelings of fear, euphoria or realization. For unknown reasons, these hallucinations tend to involve the Combine or the Union in some manner.

It is speculated that the philosophical, religious or political leanings of the user can greatly influence the content of their hallucinations. Some psychologists propose that because Benefactor cultists are devoted to the Combine to begin with, the prevalence of synth oil in their rituals can be attributed to confirmation bias.

Production
Procuring synth oil is a fairly simple process. Upon discovery of synth remains, one pulverizes or presses any malleable tissues and catches the oil as it seeps out. However, finding synth remains large enough to facilitate the substantial extraction of oil can be a challenge. The introduction of synths into the environment occurs rarely; many remains date back to the Uprising or the early post-Occupation era and are partially or wholly decayed.

Some tissue farmers grow synthetic masses optimized for synth oil production.