Yeah, I think the stocker actually tells you whether or not you have pressure. Not how much. My guess is that there is a margin with the stock sender. Once it reaches a certain pressure (like say .... 20 psi.) the needle moves up. But it may stop ANYWHERE. That's just my guess. Like Eric said, I've always heard they are "dummy gauges".
Yeah, I think the stocker actually tells you whether or not you have pressure. Not how much. My guess is that there is a margin with the stock sender. Once it reaches a certain pressure (like say .... 20 psi.) the needle moves up. But it may stop ANYWHERE. That's just my guess. Like Eric said, I've always heard they are "dummy gauges".
Mine changes after oil changes sometimes. It will go up by about a letter after I change the oil, but if it were a real gauge and not a dummy light it would actually move from like the O to the M or A sometimes. The reason they put dummy lights is because people would complain about oil pressure being too low at a cold idle, they thought something was wrong. They would bring the car to the dealer and try to get it fixed and Ford would just throw a dummy gauge in there to shut them up because nothing was actually wrong.
IIRC the stock oil pressure guage is more like a switch, and as long as you have something like 5psi of oil pressure (it was ridiculously low) then it "activated". That's what I've heard, and I have no reasons to believe otherwise since I have NEVER seen mine move at all. It's actually disconnected now.