[leofig]

When the truck is stopped, one can heard the knocking; it sounds almost like a plastic paddle were touching the fan blades when running. As I accelarate (still stopped), the noise increases. In the begining, it faded out after a couple of minutes, but now is constant.

On the subject of the 93 vs. 87; I tried 87 before and after a month of using it, my truck started to stall from time to time. The dealer recommended a new fuel pump (since I did not tell them about the gas). As soon as I switch to 97 and added some STP, the problem is gone.