My 2000 RX300 has 311k miles. Consumes about a quart every 500 miles, I have some leaks but I know it burns oil and most likely sludge buildup. I've been running full synthetic for the last 4 years and change it every few months.

In the last 2 years this noise has happened about 4 times. Usually after the car sits for a few days, but not always. Once I didn't drive it for a week and it was fine.

The sound would usually last about 5-10 seconds then go away.

This morning it seemed to last alot longer but the sound decreased a good bit and I shut it off and did not drive it. After work today I tried it again and the sound is still there but not as loud.

I think the engine might have reached its end of useful life. Most likely all clogged up with sludge?


Do you think it is valvetrain noise, or main or rod? Or other?

Here is youtube link to the sound.

 

Sounds like rod knock I think, if possible post a video of you revving the engine to 2000 and then back to idle, repeat a few times.