since i bought my truck it has always had a slight knocking which i told it was probably piston slap...recently that knocking sounds is a bit louder. I had just changed the oil maybe 600 miles ago and the oil pressure seems to be fine on the gauge. I have not notice any decrease in performance. What could be the cause of this and how would i go about in fixing it? Thanks in advance

 

Do a search for piston slap and read up. More than likely this is what you are hearing...