My pressure dropped after an oil change. Orange can. Then I swapped filters (again) without changing oil and it went up ~ 10 psi across the board. Just sayin'
Wow, My 4cyl with 310K miles on it stays between 40 and 50.
When I bought my 6cyl it was sitting near 30. the PO had taken it to jiffy lube and they put a little bitty filter on it. I replaced the filter with the correct size Bosch and it went back up to 40.
I haven't had a sender yet I could really count on. I always hook up a mechanical pressure gauge (at least once) to check my real pressure and then extrapolate.
The vast majority of senders are under, I have one now that is over (a first).
My 98 used to look that good. Now I am around 10 at hot idle. Sometimes when wheeling, the oil pressure light comes on. Had a tap in the motor for a while, but that went away. Think a lobe is flattened now. Still runs fine, but power is off a bit and mileage is around 15.