When motor oil is heated above 230degrees F, it will oxidize. The hotter you heat your motor oil, the faster it oxidizes. And that oxidized oil lacks much of its lubrication properties as well at other negative effects. The bottom line is that if you cook your motor oil, you need an oil change. Synthetic motor oil is more resistant to oxidation and can handle hotter temps compared to crude oil based oils. The aviation engine oils we use in our Continentals and Lycoming engines can handle higher temp too.
Brant Hollensbe
