Try to use thinner oil, such as 5w-30, to see if the problem goes away. I think the oil filter is leaking oil back to the oil pan after the engine is off. When you start the engine, it will take seconds to fill up the oil filter before oil reaching the lifters. I do not know much about the gasoline engine. I wonder if there is a one way valve to prevent the oil going back to the oil pan or not. Please let us know what happen if you fix the problem.