Out of curiosity I asked Zenyatta for costings on oil use but have had no reply but looked at oil cost per tonne of ore for one of my gold miners with a similar infrastructure to ZEN and they reckon on $4.75 per tonne of ore, that comprises of transport and onsite extraction machinery. I appreciate it's not apples for apples but it does show this drop in oil price will be a major cost saving factor for miners especially low grade operations.