Dear Tom and Ray:

Is it possible to determine the make of an older truck (Ford versus Chevy) based on the feel of the door slamming? A friend gave me a ride as a favor. As he pulled away, his truck screeched like he needs power-steering fluid. I'd like to thank him for the ride by surprising him with some steering fluid, but I don't know the make and model of his truck. Apparently, that's important for getting the right steering fluid. Mutual friends also can't remember his truck's make and model, but they laughed at me when I said the door closing felt and sounded like a Chevy, not a Ford. Short of a blindfolded "slam test," we don't know how to settle this important dispute. A large bar-tab bet depends on your answer.

-- Doc

TOM: I wouldn't rule out the possibility that someone with sensitive ears, who pays attention to such things, can make a distinction between cars by the sound of the door closing.

RAY: I usually can tell cars by their starter motors' sounds. And I certainly can remember a time when I could tell, just by the sound of the running engine, what make of car was limping into the garage. Not as much anymore, but they used to have unique engine sounds.

TOM: The same probably is true of door sounds: They've likely become a bit more similar over time because every door now has pretty much the same equipment in it and has to meet the same safety standards.

RAY: So I think it's possible, but not easy, Doc. And short of the double-blind slam test, I don't think we can tell you what percentage of the population can identify a car make by the sound of the door closing.

TOM: That said, I'd advise against guessing at all in this case. If the truck was screeching as it pulled away, it's more likely that he needs a belt rather than power-steering fluid. And you need to know more than just "make and model" to get him the right belt for his car.

RAY: So, here's what you do: Next time he's hanging out with you, building up that bar tab, go outside and look near the bottom of the windshield on the driver's side for the 17-character vehicle identification number (VIN). That's a unique identifier that provides all kinds of information, including year, make, model, trim level, engine type, place of assembly and the truck's birth order in the assembly line.

TOM: So if, for instance, you write down your friend's VIN, then call the Chevy dealer and ask for a belt for a truck with "this VIN," they'll be able to look it up for you and say, for instance: "Hey, dummy, this is a Ford. Call the Ford dealer."

RAY: But since belts are unique not only to years, makes and models, but also to different size engines in the same vehicle, you really need the VIN, or all of the other information, to get him the right one.

TOM: Or you could just pay his bar tab and be done with it, Doc. Up to you. Happy trails.