ACEA grade 5 oils are extremely rare so you will have to hunt for some. Hyundai dealers in Australia are having difficulties finding grade 5 as well are not happy about having to use it. I'm not aware of Mobil 1 having a grade 5 but maybe they have a different range in the US. If you go to Bob is the oil guy you will find that used oil analysis on Mobil 1 always shows a lot of iron in the oil, which indcates excessive crankshaft or camshaft wear. This is why I never have used Mobil 1 because it seems to suffer from shear.

Because grade 5 can only be had as 0W30 or 5W30 and because we have very high ambient temperatures in Australia (yesterday was 39 and tomorrow will be 40), I am using 5W40 ACEA grade 3 synthetic.