Confirm true pressure with a mechanical gauge, since the stock electrical sender can read zero while pressure is still around 10 psi. Use a quality 20W-50 oil, such as a diesel-spec oil or Castrol Act-Evo, and a good filter such as WIX. About 8 psi or more at hot idle is generally considered acceptable on these engines.
A 1997 Jeep Wrangler with a 2.5L engine and 118,000 miles has normal oil pressure when cold, but pressure drops as the engine reaches operating temperature and falls to zero at idle, then rises again while moving. A reply notes that 2.5L and 4.0L engines share an oiling system and commonly show low hot-idle pressure. The stock sender may be inaccurate, so a mechanical gauge is recommended, along with quality 20W-50 oil and a good filter. At least about 8 true psi at hot idle is described as acceptable.
