I got a 93 chevy pickup k2500 4x4 350 and this is the issue upon start up the oil pressure is 40lbs then after it warms up 10 - 20 mins. The pressure would drop to below 30lbs while driving then when I stop at a light it drops to the red line no noise as of yet did an oil and filter change and replaced the oil pressure sending switch and just to add the truck sat for 2 years. Thank u for any and all help.

 

What filter did you use? Check to see if any oil is getting to the top end. Open the oil fill cap while it is running at idle. If you didn't have any up there you should be able to hear the lifters on that truck very easily but just make sure. Make sure it's not just your cluster as well. I would get a relatively cheap oil pressure tester as well before spending money and time on a new pump. My cluster on my '90 would do this all the time. It sat for about 6 months or so.

 

Took off the oil cap had it running and its wet in there but not to where u can see it dripping or splatting around. No noise from from the valves or lifters

 

I would definitely get an accurate oil pressure reading then. If there's oil up there at idle and no valvetrain noise sounds more like and electrical issue to me.

 

Should I get a mech. Oil pressure gauge or an elec. ONE thanks all the help

 

How many miles on the motor please

 

I use a mech. one usually. I guess it's just preference lol. A bud of mine has the electric and it's pretty dead on.

 

The motor has 203,000 miles on it and it sat for 2 years.

 

With 200k miles I would say this is about normal as the motor warms up. My 93 5.7 is at 45 psi cold, at idle after a good freeway driver it's only 5-10 psi. Sometimes the check gages light even comes on. Try running a heavier wt oil.