Nissan Repair: Engine problems, oil light, dip stick

Question
I have a 1997 Pathfinder with 66,000 miles that I do not drive often.  After letting it sit for almost a month, I drove it on a weekend.  It started and sounded well, however after driving it for a few blocks the oil light came on.  I stopped the vehicle and checked the oil.  It was a little dirty but it was registering full on the dip stick.  I started the vehicle back up and heard what sounded like the valves ticking.  I immediately turned the vehicle off and had it towed home.  I changed the oil and filter and started the vehicle again.  The oil light was off and it sounded well.  However when it drove it a few blocks down the street the oil light came on again and I could hear what sounded like the valves ticking.  Again, I turned the vehicle off and had it towed home.  I have done all required maintence as scheduled and have no idea what is going on.  Can you tell me what is going on?

Thanks,
Calvin

Answer
Check the oil pressure with a known good gauge.  It sounds like you have a plugged gallery from what you describe.  Get some motor flush and start the engine up again and see if the oil pressure returns.  Do not race the engine and let it idle normally.  If the pressure does not return and the vavle noise decrease you are looking at taking the oil pan off to check for a plugged pump or fiter screen.