Puzzler Answer, Encore 5, Gas on Engine

Tom: Yeah, you call this a wingding Puzzler?

Ray: Do you remember the new Puzzler?

Tom: What do you mean? How can I remember the new one, I can't even remember the old one!

Ray: Heck! I was just waiting to see if you said yes, and if you did I was going to ask you how you could possibly have remembered it.

Tom: This is a Puzzler of old.

Ray: So I could have remembered the new Puzzler of old. It would be like going back to the future. Yes, indeed. I remember some years ago. This was some years ago.

Tom: How long ago, a long time ago?

Ray: Yeah, some years ago, I was working on something like a General Motors car, maybe like a Dodge, Dodge Dart, and I was changing the customer's gas filter, and because our sign was out being dry-cleaned that said customers are not allowed to be out in the area where we fix the cars, he was standing looking over my shoulder, making sure that I did the right thing. I was changing his gas filter, and as I did that gas spilled on the exhaust manifold.

Tom: And he leapt back in fear!

Ray: He came back, yelling, "Watch out!" Actually what he did was run for the fire extinguisher and come back to the car with the fire extinguisher pointed at my face.

Tom: And you said, "Cool out, man."

Ray: And he said, "You just spilled gasoline on the red-hot exhaust manifold. Aren't you afraid that it is going to catch fire?

Tom: And you said...

Ray: I extinguished my cigarette and explained to him, "No, actually, I'm not afraid." He said, "Well, I'll tell you an interesting story, young man." I was a young man at the time; this was some time ago.

Tom: Yeah, some time ago.

Ray: He said, "I spilled motor oil once on the manifold of this very car."

Tom: And it burst into flames.

Ray: And I said, "Yeah, that's true. That could possibly happen." And the question is,--Why is it that he could spill motor oil on the manifold? Let's assume that the manifold is the same temperature.

Tom: As what? The surface of the sun?

Ray: No, as the time I spilled gasoline on the manifold. The motor oil burst into flame, yet I spilled gasoline, which everyone knows in quite flammable. And why is it that the gasoline does not catch fire? And the motor oil does? Or am I what?

Tom: Nuts!

Ray: Wacko! Now we could have generalized this Puzzler. Say you have a hot exhaust manifold, like 800 degrees, and you spill gasoline on one part of the manifold and you spill oil on another part of the manifold.

Tom: Right. And the oil bursts into flames and spreads across, and the gasoline catches fire and the whole car blows up.

Ray: But the reason the oil catches on fire and the gasoline doesn't is interesting. They both have what's called the same ignition point. That is the temperature at which they both will burst into flame; it's, like, 752.73 degrees.

Tom: You looked it up?

Ray: Well, no, but it's something like that. They are both relatively close, which is surprising. The reason that the gasoline doesn't burst into flames is that it doesn't hang around long enough. The oil sits there and bubbles getting hotter and hotter and hotter until it finally reaches what? The ignition point. And it bursts into flames. The gasoline, however, being so volatile, evaporates, so as it hits, it evaporates and disappears because it has a very high flash point. So it's not there to burn.