OK, so you're not talking about the flash point, you're talking about auto ignition. There's a difference, but don't ask me to explain it. All I know is there is a quite a temperature difference between the two. It's kind of like the difference between the whoosh and the boom.
So far, I've found you a chart that shows the auto ignition (boom) temperatures of various combustible fuels. Now we need to find out what pressure you need to apply to the oil to get it to the temperature listed on the chart. Here's the chart:
http://www.engineeringtoolbox.com/fu...res-d_171.html