Sounds like a lifter, no worries, change it if it bothers you.

They are not to hard to change, you need to remove the cam which is pretty easy. Cost about $25 each.

If you hadn't been running Mobil 1 my sudjestion would be to try Mobil 1 and see if it goes away. But since you already are there isn't much more you can do in that respect.

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1969 280SE
2023 Ram 1500
2007 Tiara 3200