I have started to notice, what sounds like a problem coming from my engine
when it is at higher RPM's. It sounds similar to the noise you hear from an
engine that has mechanical valve lifters that are out of adjustment (loose).
Under the hood, the noise seems to be coming from the top of the engine.
The vehicle has 50,000 miles on it, and I have changed the oil every 3,000
miles since new (10W-30). Anyone that has knowledge about this I would
greatly appreciate your input.