IRAN on the top and bottom about 100hrs ago due to lifters/cam corroding (yes I use Camguard, yes I hate Lycoming metallurgy that isn't my question). I had this appear a bit early on in break in when I was will using Mineral Oil which I ran to about 30hrs. Then for the most part everything has been the same as it always had been for 15yrs and give or take 1500hrs.
Yesterday flew KLZU to KDKX and was progressively losing oil pressure. CHT, EGT, etc. all the normal. The oil temp was a little hot and then a little cold in both pictures because it is a 45-60 min ride up to 8K with a slam dunk at the end due to mountains. You can see in the first picture the progressive loss and then an immediate 10 PSI jump, the flight back to KLZU (same day) is the second picture (I also flew KLZU-KDKX-KLZU today and had same 68-72'ish PSI result).
I haven't seen anything sludgy or goofy in the oil, consumption is great, filters are clean, this is new oil with about 6hrs on it (so differing oil then the first time I saw this), etc. I am guessing some sludge coming apart somewhere? I open it to the peanut gallery.