Anything above 10psi is okay.
If it starts dropping under that, I'd worry.
Here's the problem...
Unless you have a pressure gauge that is "certified" for low psi in the 5...10...15psi range, your gauge is probably not that accurate that low.
As a rule, gauges are most accurate in the middle of their range...
So a 0 - 100psi pressure gauge is most accurate around 50psi.
Trying to get a 0 - 100psi pressure gauge to read accurate down to the 5 - 15psi range is just not reasonable.
Yes, your oil is diluted from all that rich running.
Your oil pressure is going to go up.
How much is it going up? I doubt it's going to be much...
I'd be surprised if it goes up from 10psi to 15psi.
It doesn't hurt, and changing oil isn't that much of a big deal.
Now, going from a 10W30 to 20W50 *is* going to be much more of a difference.
You're basically doubling the viscocity of the oil, and that's going to change your numbers significantly.
I think you're being a little paranoid about the oil pressure, but, on the flip side, I don't blame you.
I've been through an OPR failure and an o-ring failure, and I know what the symptoms look like - you're going to see a significant drop in *max* oil pressure at higher revs; idle oil pressure is practically "0".
Remember, the engine is under very little load at idle - 10psi doesn't sound like much, but it's enough to keep everything lubed and happy.
An engine revving under load at 3k+ RPM's is going to fail a lot faster when you cut the oil pressure in half versus at idle.
Now, I'm not talking about catastrophic oil pressure loss like...NO oil pressure, which is obvious the engine is going to kill itself in short time no matter under what conditions, but I hope you get the point of this long reply...
-Ted