If it ain't broke don't fix it!

If it runs fine then keep driving it, IMO.

I had a 1981 international crane truck with a 304 V8 gas engine in it that I bought used for the crane on the back. It would show 0 oil pressure at idle warm and would go up to 25 or so when revved up. We used that truck like that for more than 15 years. I figured eventually I would have to overhaul the engine, never had to and then I sold it still running. That truck sat there and idled most of the time while the crane was being used. My

I ran 15W-40 diesel oil in it the whole time.