Help diagnosing my buddy's truck. It's leaking oil from the gasket on the filter. Only when running. He changed the oil a week ago. Yesterday I double checked that he didn't leave behind the gasket from the old filter,and installed a new filter. No change, so I'm thinking the relief valve is stuck closed causing too much pressure and it's blowing by the gasket. I don't see any cracks to the filter mount/housing.

 

When the pressure relief on the honda I was driving failed..... it would send full pump pressure (2500psi or so) to the filter. Needless to say, the filter is NOT designed for that..... The filter would become perfectly spherical, and then pop seams..... Instantly.

What does the gauge in the dash say about oil pressure?