hey there. 1st post.
98 12v 108k 4x 5spd oil press went to zero at a stoplight the other day, did it a few times before i changed sending unit, topped of oil and checked wires to unit. still happens any rpms above idle and it bounces right back to 40+ lbs. any help will be great

 

try a full oil change. mine did that when the injector went and filled the pan with fuel.Its the cheapest place to start.

 

Could be a wonky injector but more than likely, its just the pressure sender that needs replacing.

Sorry, I dont have a p/n off the top of my head but the senders are available from Cummins. If you do a search here you should find the part number.