As an electrochemist I have spent much of my life trying to understand technical mysteries associated with various liquids and their specifications. Based on this, when I read in the latest AAIB bulletin that the fuel "in many respects exceeding the appropriate specification" I start to ask the following type of question:
Are there some components in the fuel which have secondary benefits which have not, so far, been fully realised? E.g. lubrication. If this might be the case, then concentrating on those possible benefits might be the key to the mystery.