My buddy wants me to check his oil pressure on his 02 winny 3.8l with my mechanical guage. whats the easiest place to check it ? I know at the switch but that looks like a real pain to get at looks like you have to remove the alternator and bracket to get at it? What about down at the oil filter adapter looks like there is a allen plug right above the oil filter on the front side is that a regular plug or some goofy o ringed thingy?