Witchoil clarification

From reading and running Island at the Axis of the World and the Dying Skyseer, I understand that witchoil captures souls. It is also a powerful fuel source. Macbannin is planting vials around Flint to catch souls and power the witchoil.

What I'm not clear on is whether the witchoil in Macbannin's laboratory reservoir is powered or unpowered. If the former, where did all the souls come from? If the latter, how is the witchoil going to be used to power Borne?

On a similar note, am I right in assuming that the horrific nature of the flayed jaguars means they (and the bleak golem) utilize the powered version of witchoil?

Now that my players have figured out what witchoil is and how it works, I need to be consistent in describing to them what form they find it in and where.

The reservoir has powered witchoil. Like, there are enough people who died on Cauldron Hill and whose souls were trapped there that the witchoil they produce comes pre-powered.

The vials placed in the factories were older experiments to see how easy it is to charge the oil. They used witchoil produced in smaller quantities using traditional rituals, as opposed to the eldritch machine in Macbannin's lab. They were able to reach different levels of 'refinement,' figure out what levels worked best as fuel, and then set the eldritch machine to produce that grade of witchoil.