[Axial]

Actually he is, because he also describes what the "Z-Stoff" is made of, and that is actual Z-Stoff he describes. Z-Stoff was used as a catalyst for the T-Stoff, but it wasn't one of the main fuel components.

Also, I've seen the entire footage for the refuelling, and there were two trucks: one had a big "T" on it and the other had a big "C". There was no truck with a "Z" on it.