Dear Tom and Ray:

A couple of months ago, I bought a used 2007 Tacoma truck from a Toyota dealer. The truck had 53,000 miles on it. After driving it for 5,000 miles, I took it to my local mechanic for an oil change. He, being the good mechanic that he is, checked the air filter. To his surprise, there was no filter element in there! He put one in and told me about his discovery. My question to you is this: How much damage could have been done to the motor in the 5,000 miles I drove it without an air filter? I intend to tell the dealer, but first I'd like to know what effects this missing filter could have on the truck so I know what to ask the dealer for.

-- Jay

TOM: Well, you could have lost a few neighborhood birds in your engine, Jay. Or maybe a Toyota Yaris.

RAY: Actually, you probably did no damage at all, especially if you drove on normal, paved roads.

TOM: The air filter really protects the engine when you're driving on dirt roads, when dust and grit are surrounding the car in a cloud and are being continuously sucked into the engine.

RAY: If dust, sand and grit get past the air filter (or past the non-air filter) and get sucked into the cylinders, they'll scratch the cylinder walls and lead to lower compression and oil burning.

TOM: But if you drove on regular city roads and highways, it's unlikely that much of anything got into your cylinders.

RAY: Still, I agree that it's worth telling the dealer about it. First, they made a mistake, and they should know about it.

TOM: Second, you'll solve a mystery for them. For two months, some mechanic has been wondering how he ended up with an extra brand-new air filter still in the box.

RAY: And finally, it's reasonable to ask them for some kind of extended warranty on the engine. Or at least on low compression and burning oil. If you did suck some grit into the engine and damage it during the past 5,000 miles due to the dealer's negligence, you probably won't know about it for another 25,000 or 50,000 miles, when you start noticing blue smoke coming out of your tailpipe.

TOM: So, ask them, as a gesture of good will, to give you a warranty on engine issues that could be attributed to this error, through 100,000 miles. You probably won't need it, and they probably won't ever need to fulfill it. But it'll make you sleep better at night. And tell them you'll take that filter now, too. Good luck.