Anyone who voted "Up" in this poll give yourself a hand, especially if it was not a guess.

Does the noise sound like a clattering or slapping?

Sounds like a Sewing machine is valve train.

All your B230s have some piston slap. It does not hurt anything. Jimmy57 laid it out on this page.

These red block engines have discs of various thicknesses to adjust valve clearance. Service interval is every 30,000 miles.

volvolugnut

"Or find a cleaner that is poured into each cylinder, and then removed....assuming rings sticking on pistons."

What kind of cleaner would this be?

. Swepco + on ZDDP and Boron. Used it in my 98 S70 T5 then one winter got a little thick then went with 308 5W-40. Besides the recent 303 10W-30 purchase as a booster to oil changes I forgot I have another depending what I think the car may need at the time. . https://bobistheoilguy.com/forums/threa...

I can answer some of these questions. Yes, some red blocks had carbs - maybe only Canada and Europe. I have read general articles of red block making 400 HP with Turbo and excessive fuel to prevent detonation. Not fuel miser, but lots of HP. A 6 speed Tremec trans could probably be installed with ma...

One quart/liter in 2000 miles is really nominal
Oil use. Steady as she goes with what you are doing.

It’s your money I usually do them around 5-6K on both my bmw and volvo but that’s me.

What happened to the piece of missing valve? Perhaps the chunk of valve pitted that cylinder? It burnt off and flew away. Probably stuck in TWYC. No, it did not pit anything. It was probably melted down to fluid when it departed the valve. Redline has protected my engine according to my mechanic wh...