Ford states that 5W-30 oil should be used in my 2007 Fiesta XR4, but being unaware of this at the time I used what Penrite recommends, which is 0W-50. Will this harm my motor, or are their gains to be had using a different grade of oil?
Penrite is a quality oil and the one your chose covers the range needed in the Fiesta at both ends of the scale. You could use another oil that doesn’t have the same broad spectrum and save a little money.