Intermittent oil pressure/lack of oil pressure

So when you say that synthetic will cause a pressure drop, what is happening internally that is blocking the pressure? Is it clogging the pickup, just not able to get through it with enough pressure?
I`m not saying it does-just saying it happened to me.
maybe my engine is haunted, It did come from a wrecked 69 Cuda, dont know the story:snakeman: