I have a Pontiac 2003 Grand Am 2.2 EchoTech w 150,000 miles. I have owned it since new. I have always used Mobil 5w30 synthetic oil changed at around 7500 miles. I would like to take a look under the valve cover just to look for sludge or varnish and am wondering how hard/involved of a job it is to remove the valve cover?