Originally Posted by cobalt327
There may be two bypass valves: One may be located in the filter, one may be located in the filter mount. Then there's the pressure relief spring and valve in the pump.
The pressure relief spring and valve in the pump is what sets the oil system pressure, unless the oil viscosity/oil clearances combine to raise the oil pressure beyond the pressure relief of the pump. This assumes a correctly working oil pump pressure relief assembly.
It wouldn't be a big surprise to find the pump has a different relief spring than it was supposed to have, or even that the pump valve is hanging closed. But see what you get for pressure w/the thinner viscosity oil after break in before you drop the pan.
anks, that sounds about right. Thank you too jester.