Do bad valve seals cause low oil pressure?

Ok here, the valve seals have no effect on the oil pressure. If there bad ya, its gonna blow blue smoke. The oil pressure...does the motor knock? if not there may be a plugged screen under the oil pressure sending unit that has to be fished out and cleaned. GM started putting these in around this year truck.

Bad valve seals usually only produce the blue smoke on initial startup. They usually don't affect the performance of the vehicle, but can screw up oxygen sensors and catalytic converters if not repaired. If your oil pressure is that low, you need a new oil pump. If the engine has a lot of miles on it, you might consider a high volume oil pump to compensate for worn bearings, etc.

I replaced oil pump with melling high volume, cleaned screen, replaced 'o'ring, changed oil filter, changed oil, took it to the shop, replaced oil sensor behind intake, replaced cluster, and still have low oil pressure. Mechanics say I have no lifter noise, no knocking, no abnormal noise coming from motor. No signs of anything wrong but my oil pressure's actually low. Manual gauge says <10 , now they say I need a new engine. I say I need to stay FAR away from GM