Its 1988 1500 chevy truck with a 350, I just got it about 2 months ago and have been fixing one thing after another ,and I put a 2 inch oil pressure gauge in cause the one in dash wasent working. I changed the oil about month ago and oil didnt look to bad but i took the vaule covers off to change gaskets and too my surprize there was so much sluge from them not changing the oil right and not good oil. I did clean the covers and top of heads and was carefull about droping any sluge down the oil gallerys. so after all that been driving it alittle maybe 50 miles or so and oil pressure at idle, when stopped , would be between 5-15 pds and driving about 55 mph would be around 50 pds but now its between 20 -40 driving ,and below 5 pd mark at idle . I was going to change oil after driving it about hundred miles but fixing to change it today. but i guess my question is ,if the oil pressure at idle is about 5 pds or so, that should be ok im guessing. I dont drive truck much ,maybe 50 miles or less a week. sorry so long guys . and plus the air temp is around 95 , and my engine temp while driving is around 165.