I have read through some threads here, and other sites, regarding low oil pressure on 5.3L. They have discussed sensors and such, but I have not seen my particular issue. So I will try to give as much detail, and apologize for being longwinded. I have an '02 Silverado 5.3L. At the beginning of this story, 2 years ago, it had about 200K. It has 237K now. Back then I had the oil & filter changed at a locally owned quick lube. I drive 8 miles one way to work normally, but a few days after the oil change i drove 100 miles one way, to a work site. On the way home that afternoon, on 4 lane at 80 MPH i start hearing this tapping noise & freak out. I slowed way down, exited, sat a bit, checked oil & it was fine. Took off again with heart rate higher than RPM, still 80 miles from home. Did it again, but I made it & went to my mechanic the next day. In our discussion he asked if i had the oil changed at "Franks". Uh, yes. So, i'm the 4th one he's seen and he says "Frank" is using cheap imported filters that are collapsing under pressure. My guy changes the o & f and i'm fine for months till i try to pull a loaded trailer, then the oil pressure drops. Once it falls below 40 the tapping starts. So, this has gotten progressively worse over the two year span, to the point that, with no load, just normal driving, between oil changes the pressure drops lower and lower at idle(around 40), and doesn't stay as high (around 50 was normal) when driving. I'm taking it to him this week, but i really want to hear from some other folks before I do.