That actually helps. Thanks.
A phone limits the frequencies it records, but I hear a lot of valve lifter clicking, and something lower end or piston 'rattling'; could even be the cam chain in the background, but nothing that doesn't sound similar to my relatively unused FJ's engine (~37k miles). My logic is that 0-20 synthetic oil doesn't dampen much, and just about every part that is oiled (has a clearance tolerance) makes some noise, and it all adds up.
Grab a long screw driver, point it at the engine in places and stick your ear to it. It helps isolate where the noise is coming from. I once found a bad alternator bearing that sounded like it was a rod about to blow. Bought that truck for $100 because the guy was certain it was the engine. A $35 rebuilt alternator and 20 minutes and I had a great work truck I drove for years.
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On second listen, I do hear a 'knock' you might be asking about, but it doesn't sound like a rod knocking. At 1000rpm idle, a rod is spinning at 16Hz, not 2Hz. So the sound's rate leads me to belts, chains, etc. Could be a slapping fan or timing belt, a bad tensioner, etc. Again, a rod or screwdriver (or stethoscope) will help isolate the noise.
I'm not a mechanic by trade, but have been inside a few engines. And, it also doesn't sound too much different than my newer 2012 FJ engine. The fact mechanics have been near it and heard it and didn't say anything, I'd be biased to say it's normal.