1993 F150 5.0L 165K

Oil pressure used to register at the "m" in normal on the gauge. The oil pressure has recently changed and registers between the "n" and the "o" in normal. The engine temperature has not increased at all, there is no clanking or clicking that I can detect. It runs fine for extended periods of time...300 mile trips...

I rencently added the zmax product set (oil,gas,trasmission) additives...www.zmax.com (hope this wasnt a mistake...)

should I be concerned about this? it has never registered at 0 or at max, just seems to have dropped a few notches...

 

I just went through the same thing on my 89 351. All it turned out to be was a bad connection at the sending unit. I just pulled the wire off the sneding unit and put it back on a couple of times and everything went back to normal.
Hope your problem is as simple as mine was

Good Luck

 

I have had that happen on an almost new engines and it was because of sludge trapped inside the pressure sensor. Used some spay cleaner and it has been good for two years. On another Ford truck the gauage in the dash sticks when it is very cold. Once the truck is warm you tap on the gauge and it moves from O to M. Actually look up all the info on this site as the gauage is really an idiot light.