MAGLIOZZI

Dear Car Talk: I have a 2009 Ford Edge with 125,000 miles. It has been very reliable since I did the timing chain, water pump, plugs, etc., at 100,000 miles. Recently, the oil light has been coming on intermittently, but only when slowing down or stopping. As soon as I start moving again, it goes and stays off. I check the oil level frequently, and my garage floor shows nothing leaking.

I took it to my local shop. They changed the oil but found nothing causing the light to come on. It stayed off for a week, then came back on. I brought it back in, and they still found no direct reason for the light coming on. But they did recommend a complete engine rebuild costing $11,800.

Two questions: 1. Will having that work performed triple the value of my vehicle? If so, I will have that done. 2. If not, would you recommend that I get a second opinion? And any suggestions what they should be looking for? — Bob

Heck yes to a second opinion, Bob. There is a reason your oil light is coming on, and you need to know what that reason is, so you can make an informed decision about whether to fix this car or drive it into the nearest body of salt water.

If you’re really lucky and you’ve lived a good, clean life, it could be your oil pressure switch. That’s the device that reads the oil pressure and turns on the “Check New Car Ads” light when the pressure is too low. If that switch has gone bad, replacing it is trivial. And if that’s the problem, you could be back on the road for less than $100.

You need to go to a shop that will put their own oil gauge on your engine and read the true pressure themselves. If the gauge tells them that the pressure is, in fact, too low, that means that your oil pump and/or your bearings are shot. And your previous shop has already told you how they’d fix that: Rebuilding your engine for $12,000.

Will doing that triple the value of your car? Well, yes, but only because your car is worth very little with an engine that needs to be replaced. This car is probably worth in the neighborhood of $5,000 with a working engine.

So, the question is, how much do you like this car? Would you like to drive it for another three to five years? And is it otherwise in very good shape? If the answers to those questions are yes, you can shop around and look for someone who’s willing to put a used or factory-rebuilt engine in this thing.

A good factory rebuild (which should come with a multi-year warranty) will likely cost somewhere between $4,000-$5,000 just for the engine. Probably $8,000-$10,000 installed. Since the rest of the car has 125,000 miles on it, a used engine, while obviously less reliable, would be a lot cheaper.

But before you go either of those routes, think hard. If a second shop puts an oil gauge on it, and the spec is supposed to be 20 psi at idle, and yours reads 17 (or 4), I’d rather see you put that money toward a new or newer car. I can’t, in good conscience, recommend you spend $10,000 to put a new engine in a car that’s already 16 years old.

In the meantime, I’ll say a novena for an oil pressure switch for you, Bob.

Got a question about cars? Write to Ray in care of King Features, 300 W. 57th St., 41st Floor, New York, NY 10019, or email by visiting the Car Talk website at www.cartalk.com.