It should not be that 'sludged' up after 5000. Unless you use Quaker State, drive in REALLY dirty conditions, and have never changed the oil.
Did the lifter noise start "all of a sudden", or slowly show up? Have you changed ANYthing on the engine recently or around the time the noise started?
The cheapest thing by far to try is to change oil and new filter. Another easy thing to try is to buy/borrow another pressue guage, and check you really have 60lbs at the sending unit.