One thing to know is that, as stock, they use a pressure switch, rather than a sender. The instrument gauge, as such will show only two states: Normal or Low. If your sender is small, like a cubic inch, then it is a switch only. A true sender is more of a container shape, a couple of inches long. There is a procedure to install a proper sender and a modification to the gauge cluster to give you true oil pressure. It is not hard, there are a few articles here on the subject.
So, assuming your Exp has not had this modification, your oil pressure is crossing the 5 PSI line, which is what the original pressure switch flips at.
Which means your oil pressure is low. In my mind, there is really nothing preventative to deal with this. If you are in a warmer climate, I might go to a heavier oil. In a colder climate, you will starve your engine with thicker oil, so you need to stay on spec.
What makes low oil pressure? Sometimes it's the pump, but rarely. It can be in the cam, up in the heads, but you would hear it. Probably the issue is... damn, sorry, this is not pretty. Probably, it is loose main bearings. Main bearings are just about as deep as you can get into an engine.
There are some oddities. A clogged oil return from the top end, but you would get a low oil light.
IMHO, go a grade deeper in your oil. And, understand that your engine is near the end of it's life. It may be time to move on.