My 97 sr5 has had a slow oil leak for some time now. I've put off fixing it for long enough. I've created a bigger problem by letting it go for so long (I know, I'm an idiot). I believe the leak is coming from valve cover gaskets however, I need to clean the entire undercarriage to help pinpoint possible other leak points. What would you suggest I clean all the oil off with? I've tried degreaser and a water hose. It didn't touch it. Thanks in advance.