Hi Ed. After you've checked it a few times, don't worry about it. I haven't checked mine in 3 years plus. No issues! I would be careful about block sealer. My radiator had problems flowing well because of too much sealer before I got the car. Good to see you're still around. Ron W
You said you heard the noise after putting on a muffler. Make sure the muffler isn't loose before rebuilding the engine. If you have the pan off, measure the forward and back movement. If it is excessive, then you can worry. Ron W
As Tom has indicated, you are reading the pressure required to push the oil through the filter. When the filter is plugged it reads high. That's one way to tell. Mine exceeds 20# when revved up cold. It is full flow (no by-pass) and all oil must pass through the filter before flowing up into...