Originally Posted by bdbrown66

... but essentially it said that the AC Delco PF48E filter, which is what is specified in the manual, can cause low oil pressure indications. If so, it should be replaced with the UPF48R filter. I looked under the truck and could see that it was a blue oil filter, so I suspected that it was probably a PF48E. A little further research indicated that the Mobil M1-113 filter was identical to the UPF48R filter, and was available at my local AutoZone store. So I bought 6 quarts of Mobil1 5W-30 and an M1-113 filter and did an oil change. Lo and behold, the oil pressure went right back up to 43+ on a cold start, 40 driving down the road, and 30-35 at idle. Problem solved, to my great relief. Good luck with yours!