Does that engine knock spell doom for my Buick?

Dear Car Talk

Dear Car Talk | Dec 01, 1995

Dear Tom and Ray:

I have a 1986 Buick Century which has been a great car (aside from having the steering rack replaced twice). The only problem I have is that there is a tapping in the engine which lasts for a couple of minutes after starting, but only when the engine is hot. The noise is louder in the summer than the winter. My mechanic tells me not to worry about it. Is he right? Or is he just sick of working on my car after 170,000 miles. Should I be planning the demise of my beloved Buick, or do I have another 50,000 miles or so to enjoy her?
Sleepless in Smithfield

TOM: Dear Sleepless: If the "demise" you have in mind involves anything more intricate than, say, taking off the plates, you may want to start planning for it now to give your self a head start.

RAY: My guess is that you have low oil pressure. Oil is at its "thinnest" when it's hot, which is when you're experiencing symptoms. And low oil pressure could be caused by a weak oil pump, a worn out crank shaft, or worn out bearings. And in your case (with 170,000 miles) probably all three.

TOM: So unless you're willing to spend a couple of thousand dollars on this car, I'd throw in some 20W-50 weight oil or some overripe bananas and see how long you can put off the inevitable "flickering oil light syndrome" aka "the death knell."

RAY: It's not necessarily imminent. You could get another 10 or 20 thousand miles out it if you're really lucky. But that assumes that nothing else goes horribly wrong before the oil pressure drops below the Mendoza line.

TOM: Which is what your mechanic was obviously counting on. The reason he told you not to worry about that little tapping noise is because he probably knew the transmission was about to fall out anyway.

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