Oil isn't going to carry much charge, unless you dope it with something,
maybe little particles of some polar stuff. Or, maybe, tiny wire fragments.
Then, the charge has to REACH the particles, THROUGH the oil, which I think
wrecks the whole idea. You don't want a very good insulator to interfere
with the charge transfer.

Thanks for the thoughts. Why can't oil carry much charge, but a nylon belt can? I don't doubt your answer, but as more of a mechanical guy, I'm not sure of the reason.

A couple of days ago I was thinking that it might be possible to mix the oil with thousands of tiny plastic balls which could carry the charge. Or hollow metal balls, but they might not go through the pump. The pump can cope with a maximum particle size of 3 mm and, depending on the head, can deliver a flow rate up to 60 litres/minute. But charging the balls might be difficult.

Chris