Dear Tom and Ray - Is there any way to test a car interior for carbon monoxide or other deadly fumes? I have to leave a window partially open when I use the air conditioner or heater. On trips of 100 miles or more, my dog and I become ill. I have had the air conditioner checked out. The smell is like burning oil, but the oil level stays the same. - Cora
RAY: It's about time you wrote, Cora. We got a letter from your dog a month ago!
TOM: Actually, Cora, I don't think it is carbon monoxide. If it were carbon monoxide, you wouldn't smell anything. That's what makes it so deadly. You don't even notice it until it's too late.
RAY: I'll bet it is burning oil that you smell. There's probably a small amount of oil leaking from your valve cover onto the hot exhaust manifold in your engine. And the fumes are being carried into the passenger compartment by the ventilation system. And that smell would make you sick.
TOM: And the oil level could stay essentially the same because it doesn't take much oil at all to make a whole lot of smell. A few drops is all it takes.
RAY: Have your mechanic look for signs of burning oil on the manifold. If the valve cover is leaking, its gasket can usually be replaced for a lot less than $100.
Dear Tom and Ray - A friend and I were driving through rugged mountains with grades up to 15 percent. We were in my 1991 Toyota Camry V-6 with automatic shift. While going down grades, I suggested that she put the car in second gear to help with the braking. I have been told by several people that this is the best way to handle steep downgrades. She said she had been told never to do that because brakes are cheaper to replace than transmissions. I'm in a quandary. Who is right? - Rose
RAY: You're right, Rose. It's true that brakes are cheaper to replace than transmissions, but that's irrelevant here.
TOM: First of all, you wouldn't be doing any damage to your transmission, so it won't need to be replaced.
RAY: Second, if you overuse the brakes, they won't work at all. And then you WILL have to replace your transmission - and your arms and your legs and your skull.
TOM: When you overuse the brakes - like by counting on nothing but the brakes to keep you under control down a long, 15 percent grade - those brakes will overheat. And when they overheat, the brake fluid boils. And when the fluid boils, no more brakes!
RAY: Fifteen percent (that's 15 feet of drop for every 100 feet of length) may not sound like much. But over some distance, you'd be amazed at how much speed your car will build up.
TOM: So you're absolutely right, Rose. On a long, steep downhill, you want to use a lower gear to keep the car at a comfortable speed so you can be stingy with your braking.
RAY: By the way, we don't recommend downshifting to slow down in normal stop-and-go driving, or on hills of a couple of hundred yards or less. It's not necessary there and it just wears out the clutch prematurely. But we absolutely recommend it for long, steep hills.
RAY: Hey, did you hear that our new pamphlet, "Ten Ways You May Be Ruining Your Car Without Even Knowing It," is a million seller!
TOM: That's not what I said, you knucklehead. I said I had a MILLION of them in the CELLAR!
RAY: Oh. Well, it still has lots of good information on how to make your car last forever.
TOM: Order your copy of "Ten Ways You May Be Ruining Your Car Without Even Knowing It" by sending $3 and a stamped (52 cents), self-addressed No.10 envelope to Ruin No. 1, PO Box 6420, Riverton, NJ 08077-6420.