My 89’ shows it is dropping pressure after warm up. If I stop it shows on dash as dropping to 5 lbs, but driving runs at 35-40. I have replaced the pressure sending unit, same issue, new high pressure/volume oil pump, same issue. Is there any other sending units related to oil. Hoping its not a pull engine for rods and mains.

 

Welcome to Chevy.
How many miles; burning much oil?

 

125k, not using oil……..