exactly.
@Chief2025 the flashpoint of gasoline is irrelevant. What matters is the vapor pressure of a gasoline/oil mix at varying temperatures.
What you'll find is that gasoline is a mixture of varying hydrocarbons just like diesel fuel and motor oil are. And so you cannot "cook off" gasoline-- you actually only cook off certain portions off it. Exactly the way a distillation column works. The light fractions of fuel evaporate very quickly. The heavier fractions never evaporate.
By way of general education--
Mixtures of hydrocarbons have a "distillation curve" that shows the range evaporate and boiling points for different components of the blend. It's common for a distillation curve to be defined by "initial boiling point" or IBP, T10 (the temperature where 10% of it is evaporated, T50, T90 and the FBP or final boiling point. These five points and the interpolation between them are generally what is meant by "distillation curve" in the context of fuels and oils.
Here's some homework.
What you will find is that the T50 point of gasoline is right around typical oil operating temperatures of 90-110C. That means your standard oil temp is only hot enough to cook off about half of the fuel's blend of hydrocarbons; the heavier half will stay in the oil almost indefinitely.
