I have a 1983 International 4X4 truck with a 345 gas V-8 engine. It is a old ultities company truck with a 7.5 ton crane on it.
I bought it about 15 years ago just for the crane and the truck came with it.(that's what the dealer told me)
I figured I could rebuild the engine since I had rebuilt other International gas engines.
This engine has no oil pressure at idle, as soon as you rev it 100-200rpm the gauge moves.
This truck is geared real low and screams out on the road, hi rpms.

It's still running with no work done to it now for over 15 yeras.

No we don't drive it 8 hours a day, but we did for like 10 years. It mostly sit's nowadays but has never gave up and it has almost no oil pressure at idle.
Now I did rebuild the trans twice and the transfer case once, but never the engine. lol

To the OP, I say drive it until it dies, it might be a long time from now?