FWIW, the 4.2 in my jeep has very low oil pressure too, not that I actually have an oil pressure gauge hooked up. At a hot idle, one lifter will bleed down and start to clack. At an extended hot idle, two lifters will bleed down. I don't care if it dies, I've got a 5.2 magnum waiting to go in. I've driven it as a daily driver around town this way for the past 8 months. Taken it down the trails, off-roading, trips on the highway, sitting idling in the parking lot, etc. Never give it an oil change, just add because the rear main seal pours oil! Hasn't died yet!