05 Silverado possible false oil pressure reading?

[Brad OSullivan]

New to the forum here, and I have a 2005 chevy silverado 1500 with the 5.3L. I drive to and from michigan from chicago for college every couple of weeks. The last time I drove up to michigan 2 hours into my drive the oil pressure gauge started slowly moving down from 40psi. Every 10 minutes it seemed it moved down a notch until it got to 15psi and then I pulled over just to investigate because the truck was running perfectly normal and no warning lights or anything were on. I did a walk around, no leaks, no engine noise and the oil level was in the same place as when I left. Also when I stopped the pressure gauge dropped to 0 at idle and the truck idled normal. I continued to drive till i got to my destinations 30 minutes later. The next day when I started it back up the oil pressure is now reading normal and has read normal for the last week. I went to tech school and I know my way around an engine and i'm almost positive this isn't a mechanical issue, im thinking its the oil pressure sensor or sending unit or it could be the gauge itself because first gen silverados are famous for bad gauges but i feel if it was a bad sensor there would be warning lights? Not sure though, any of you guys experience an issue like this or have any idea of what to check or what it could be?? Much appreciated!!

[muddkatt]

Probably a bad stepper motor, but it is possible for a filter to be stopped up, oil pump failing, etc. Hook a mechanical gauge up to verify oil pressure.

[carkhz316]

If the oil sending unit is is reporting 0 psi oil pressure, you'll get a warning in the driver info center in addition to the gauge readout. Plus, it would be knocking/ ticking like mad. I will bet money that it is the stepper motor that is failing. I rebuild these gauge clusters as a side hobby and it's very common.

[Brad OSullivan]

9 minutes ago, carkhz316 said:

If the oil sending unit is is reporting 0 psi oil pressure, you'll get a warning in the driver info center in addition to the gauge readout. Plus, it would be knocking/ ticking like mad. I will bet money that it is the stepper motor that is failing. I rebuild these gauge clusters as a side hobby and it's very common.

Yah that's what I figured, is it weird that the gauge has been reading normal you think or no??

[Brad OSullivan]

2 hours ago, muddkatt said:

Probably a bad stepper motor, but it is possible for a filter to be stopped up, oil pump failing, etc. Hook a mechanical gauge up to verify oil pressure.

Yah good idea I forgot about that.