I don't think i paid much attention to this until now but what does some of your oil pressure guages read at operating temp. (idle and driving?) Mine shows just under 40psi when idling and just over when driving.

 

That's really good. How many miles on your truck, and what engine do you have in it? Also, is it 2wd or 4wd?

 

that's also normal.

 

Mine stays right around 40, regardless of what's going on, even when the little Low Oil Pressure light comes on.....

 

Dodge oil pressure gauges suck. Get a mechanical gauge.

 

That is VERY true.

 

Is it the gauge, or the sender that is the real short fall?

 

Between 40-42 regardless of idle or driving.

 

On the 98, I think the PCM gets the signal from the sender, and then suggests to the cluster where to point the needle. On the older trucks, sender is connected directly to the gauge. The sending units, on the whole, suck.... Read my above statement.

 

I've noticed the sender units tend to leak if you look at them sideways.
If you have to remove it for anything, may as well plan on a new one... if it doesn't leak, it will soon enough.

Of recent years, I've noticed the gauge takes its time to get off the mark when you first startup... checked it with a manual gauge, and pressure is up straight away.

But as to the original question; I also see 40psi at speed or idle... if low on oil, I'll see a ~2psi drop at idle on real hot days.