Every time I start my truck, the oil pressure gauge is zero. If I shut it off and restart it right away, I get full oil pressure. Drive it a mile or so, shut it off and you have to go through the same process again. I had this same scenario once or twice, so I took it to garage and they replaced oil sending unit and change oil and filter. Now it happens every time. Being a Volunteer Fireman, this causes delays that I can't wait for. Help??

 

Need to check wiring. I would also recommend a direct reading gauge. To make sure you have oil pressure.

 

These Hemi sending units are garbage. The dealer ones are bad, but the aftermarket ones are even worse.