Well, at 180k and zero problems of any significance, I guess it was due. I've been having intermittent low oil pressure since my last oil change, or at least I first noticed it when I started it to check for pressure and leaks after changing the oil a couple of months ago. My first thought was oil filter and I was going to replace the filter, but it seemed like it was getting better before I bought another one, so I kept driving it to see if it went away. This last weekend it was time for another oil change and the intermittent low pressure had seemed to be getting worse, but I talked myself into believing it was the sensor due to the intermittency. So, I changed the sensor, and....no difference, pressure looked exactly the same so I thought OK, must be the filter. I changed the oil and filter next and this time put an AC Delco filter on it (I usually use MobilOne). For reference, on a cold start the pressure is around 20-25psi, but when the engine idles down to around 600 RPM the pressure will drop, sometimes as low as 5-10psi. As long as the engine is running above 1000 RPM the pressure stays in the range of 25-40psi, and usually after running a while it will be more normal and get up to 50-60psi at higher RPMs. I've owned this vehicle since new and it has had the oil and filter changed religiously well before the required service interval. I've always used MobilOne synthetic and filters. No oil leaks or burning oil, in fact, there is very little oil loss between changes. I usually get about 5 1/2 quarts when I drain it. So now the question is what is the problem? I know that the pickup tube o-ring is known to be a problem on these engines and another possibility is the pump is going bad, or a sticking bypass valve which again is the pump. However, neither of those is a fun job, so is there anything else I should be thinking about before tearing into it? I was planning to do the overfill test to see if it's the o-ring, but haven't done that yet.