03 escape has an oil leak,knocking sound-sound changes depending on rpm, any ideas?

Did your vehicle run out of oil? There also may be a seal that is broken within the system. It should be looked at by a mechanic as soon as possible before the engine blows. I had a chevy malibu that ran out of oil and after that the engine was never the same. After taking it to the mechanic, they found a crack in the manifold which was a result of running it with no oil. Engines get very hot when they are running and they need the lubricant so the parts don't seize up. Good luck