I just bought an 89 Camaro. I thought that I had taken all the appropriate precautions. Took it to a mechanic, etc. Well, 3 days after I bought the car, I changed the oil.It immediately started to knock. I went back to the person that I bought it from and he says "I just had the heads replaced, so there was nothing wrong with the car when you bought it.)He obviously assumed that because I am a woman, I would not realize that the car had to have gotten very hot to need the heads replaced.I would like some other opinions on what might have caused the knocking rod, and also what they might have used in the oil, to quiet the knocking.