Dear Tom and Ray:

I own a 1978 Cadillac Coupe Deville with 84,000 miles on it. As far as appearance, it is in excellent condition and is my pride and joy. Recently, after leaving my house and going just one block, I stopped for a stop sign and, when I stepped on the gas pedal, the car refused to go although the motor was still running. It wouldn't budge. I was able to get the AAA people to tow the car to their garage. They immediately put the pressure on to sell me a new transmission at half price. I called my regular mechanic, who is highly respected in the community. He suggested I have the car towed over there, which I did. He put in a new "screen?" Everything seems perfect now. However, he did say that I may really need a new transmission in the not-too-distant future. This makes me very apprehensive about going any great distances. Should I consider getting a new transmission now, even though the car is running fine at the moment?
Sarah

RAY: Gee Sarah, for the life of us, we can't understand why you didn't let those nice men sell you a half price transmission.

TOM: Actually, Sarah, you were absolutely right to wait. Transmissions slip all the time. When the transmission fluid hasn't been changed for a long time, the filter (sometimes called a screen) gets all plugged up by little pieces of the transmission, which disintegrate over time. This is normal.

RAY: But when it gets really plugged up, the fluid can't go where it's supposed to go, and then the transmission stops working. There's usually some warning before that happens. But my guess is it's been slipping for weeks and you just haven't noticed it.

TOM: Changing the filter and fluid often does the trick, as it did in your case. The question is whether your transmission is disintegrating at a normal rate (with a half-life of about 60,000 miles) or whether it's disintegrating much faster than that (which is why your mechanic thinks you MIGHT need a new transmission before too long).

RAY: Here's how you find out. Wait a couple of months, then go back to your mechanic and ask him to change the transmission fluid again. If the transmission fluid looks pink and clean, then there's probably nothing to worry about. What plugged it up was probably just general gunk that accumulated over 84,000 miles.

TOM: General Gunk. I think I served with him at Fort Dix in 1959.

RAY: On the other hand, if the fluid is dirty, or worse, if the filter is plugged up again, then you should just go ahead and put in a new transmission. You say this car is your pride and joy, and it's clear to us that this worrying about your transmission is taking away from your enjoyment. My philosophy is if you're going to need the repair anyway, why not do it now and enjoy the new transmission right away?

TOM: Right. And if you're really lucky, those nice men may still have that half-price transmission available!