Note: I once had a Ford Bronco 400M a couple decades ago that registered 4-PSI
!! That was a hot engine at idle with the AC on ...in gear. I bought it used. At first it bugged me, but it sounded fine...ran fine. Eventually I got over it and ended up putting a lot of trouble-free miles on it. My plan was to put new bearings in the engine, but never did and it never did fail...I sold it to a guy who also drove it for yrs. I had several M engines which were real low on PSI (they were notorious for that!), but they continued to chug along and had well into the 150k+ mile range when I sold them.
Most of the newbie morons out there with "Internet-wisdom" are going to try to put you into a freak-out spin mode on low oil pressure. But you have to remember the number I've giving, and that your warning is coming on with a hot engine on a hot day, with the AC on and the vehicle in gear at low idle. That should be as low as it'll ever go. Which is when you're seeing the oil pressure warning. Remove those factors and the pressure goes up a little with each factor removed. Driving down the road yours might be at 30psi?? Or 35psi. Both of which are perfectly good. Yes it does indicate wear in either the bearings or the pump (probably both), but, so what?? Your whole H3 has wear all over the place. Make suree you bleed the air out of your oil pressure testing gauge's hose too, b/c that will lower your oil psi reading when testing. Add a QT of 10-40 in it and you'll probably gain a few PSI. And use a good filter, not a Fram cardboard unit. So you have to put things into the proper perspective.
Another issue that affected these Atlas engines is at some point ...on some engines, the timing chain guide plastic would ...or 'can' fail. That leads to plastic pieces in the oil pan which can plug the oil pick-up tube. But it's usually accompanied with some loud engine noises as the timing chain can be metal-on-metal at that point. Not likely your issue if you're not hearing any funny noises.
