Oil changes have been every 4,000 miles or so - some a little more, some less. Synthetic 5w30 - brand depends, typically Valvoline or super tech

Thanks for the reply. I did change the oil after getting home and have the same noise. I've owned the sub since 70k or so and I've never done an engine flush. Any thoughts on doing this now? I could also switch to a thicker oil - currently running 5w30.