Don't know why he'd need penetrating oil on it. The entire assembly is bathed in engine oil it's entire life. I've never seen rust anywhere inside the rocker cover of an engine that has a functioning lubrication system.I think some are getting a little ahead of what must be done. 1. Try penetrating oil on the adjuster. Leave it an hour or two to penetrate. 2. With a small hammer start tapping lightly on the adjuster and the lifter that contains the adjuster. Do that for about 10 minutes. If it is rusted in, this will help the oil and break up some of the rust. 3. Heat the lifter with a butane bottle and while heating tap the adjuster. After you get the screwdriver out of the freezer that has ben there for and hour and while the lifter is hot, try to move the adjuster while also tapping the top of the screwdriver.