That oil may be fine, but I quit using Castrol when Mobil sued them over the term synthetic (and lost). Basically the term synthetic doesn't really mean no dino oil in it. I like Amsoil 10-40w although it's expensive even with a discount. Harley didn't like synthetics for years but then realized their bikes would run much cooler with less wear so now they use it.
What Are Synthetic Lubricants?
What Are Synthetic Lubricants?