it doesn't sound that far fetched. besides, the mechanism is a bit complicated, unless you have at least some chemistry background. i don't know it offhand, but i can tell you that temperature is vital to any reaction rate. temperature gives the molecules the activation energy necessary to complete a reaction, and is a catalyst for most every reaction, even exothermic ones. so it makes sense that oxidation could be highly accelerated at certain temperatures. what temperature that is, depends on the reaction. another thing, oxygen is everywhere bro. O2 molecules are in the oil, and in the air above the oil. just cuz you can't see it in the oil, don't mean it ain't there. how do you think fish breath underwater? it's called diffusion...and all gases will diffuse through fluids at a rate proportional to the partial pressure (ie the partial pressure of CO2 in soda cans is kept at 5 atmospheres, so that the equilibrium is shifted to the extent that the soda will keep it's carbonation. but at lower pressures, after you open the can, the gases can escape).