Whats that noise coming from my 318?

Chryslerkid said
what is the purpose of using "marvel mystery oil"? if it turns out to be a stuck lifter, how would i get it unstuck? machine shop necessary in that case?

Either the marvel mystery oil and then a fresh oil change fix the lifter

or you pull the intake.

Remove the rocker arm assemblies ,the push rods and then the lifters.

Install new lifters with cam lube on the bottoms and reassemble the engine

Should take a couple of hours , you will need a set of lifters

cam lube and valve cover and intake gaskets.

And make sure you drain the coolant before pulling the intake