Archived Losing Oil Pressure at Highway speeds?

[MikeLong]

I've got a 1993 D250 w/only 200K+ miles. This week on a 5 hour road trip i kept "losing" oil pressure on my stock gauge. It is normally a little over the 1/4 mark. After driving at 70 mph for several hours, the gauge would drop the 1/4 to the first (or once less) mark? I would slow down, pull over, & it would be right back to "normal". I do seem to be losing some top end speed when this happens. Whats going on here?

 

[WBraico]

My 98 1/2 did the same thing this weekend,The weather was around 100 deg. today, I had stopped to talk to a friend for about 5 minutes ,I started the truck and drove onto the highway and noticed no oil pressure I pulled over and opened the oil fill cap to see if oil was flowing over the rockers and it was. I shut it down for about 5 min. and restarted the truck And then the oil pressure went back to normal, Is this a glitch with the electronics ?

 

[Dieseldemon]

Cummins has an updated presure spring for that year truck it will increase the presure 3 or 4 psi