Lomapaseo,
I have no idea about the full facts and figures from the fuel and oil systems and haven't seen them.
I believe you know (from past postings) the engine oil system is still pressurised up to 10 minutes after shutdown.
So the theory is until then, the contaminated oil system by being pressurised and venting could be feeding the fire.
If there was another issue to compound the problem, IE a fuel leak in the pylon, that I do not know.