I can't fathom why you would change good quality oil every 4000Klms, and totally wasted by not changing the oil filter at each change. Oils are designed to be changed at around 10000klms, filters must be changed every oil change, your engine is totally worn out, I have a 3.5 sitting outside that has 385000klms under it's belt and the cam and lifters are the only parts that show excessive wear.
I would change my oil and oil filter change periods and get full use of the oil and I would paint the Foam air filter green and throw it into tall grass, if you want the best from your new motor, Regards Frank.

