Okay I have a 91 s10 blazer with the 4.3. Recently oil pressure gauge jumped around bad and replaced oil pressure switch today it fixed that. Now when car first starts oil pressure is at 40 psi then after 10 to 15 miles drops to 20. As I drive eventually hits 0. If I shut it back off oil pressure goes back to 20 for a very short time then works back to 0 any suggestions anyone?

 

do you have enough oil in it? could be getting low?

 

Yes I do I just replaced oil cooler lines bc they were leaking so I just topped it off. But my bad I just looked at it and I didn't fully tighten the oil pressure switch. Hope that's what caused it

 

more than likely. it seems like its always the simple stuff huh?