Hi- I'm breaking in a new Mustang GT (4.6L V8). The factory suggests that I use a good quality 5W-20 weight oil. I was thinking of running 5W-30 Mobil 1 for 3,000 mile intervals, but I am worried about seepage.I would like maximum protection, not maximum leakage. I had a 01 F-150 with the same ltr. size motor. I had two HG leaks fixed at 19,500 miles. Could it be the Red Line oil I was using? I know that cars and truck typically aren't supposed to leak. Should I switch to syn.? should I switch viscocity? What is you opinion? Thanks. *PS does Mobil 1 make a 5W-20? If so, where can I pick up a couple of bottles?