Weird issue, need advise.
Runs and sounds normal and will drive normal with no sounds for days at a time. However a few times now I have gotten a very load valve train noise at all rpms when warm, it will sound like no oil but the gauge is between 35-50 depending on RPM. What is strange is it will go away on it's own and not come back for weeks on end. Yesterday I was heading home and suddenly it sounded like the rocker arms were falling off, I threw it in neutral and the noise was very loud at all RPMs, I pulled off at the next ramp (about a mile) and by the time I got to the stop light the sound was gone. I drove home the remaining 40 miles with no sounds.
What could be doing this?

