No doubt Amsoil is a fine oil, but one thing any oil or filtration system can't do much to combat is fuel dilution. DI engines like the Focus are prone to fuel dilution of course and we don't have a ton of real-world experience to gauge how big an issue this will be for us. I detect a little gas odor whenever I check the oil, which makes me wonder.That was once an issue with Signature Series, but now all passenger car formulations have API SN levels of ZDDP, so it's down to base stock choice.
Here are details on what the problem is with API certifications, how it's biased on petroleum base stock swapping, and discriminates true synthetic.
Standard length - Amsoil EA15K51
Long version - Amsoil EAO34
I dropped the factory fill at 945 miles, soon as I knew the piston rings were fully seated. I then switched to a true synthetic Amsoil 5W-20 Signature Series and bypass filtration system. This will allow me to make two year oil changes if I desire, or 25,000 miles.
For a car without the bypass system, one year or 15,000 miles is easy. Whichever occur first.
My point is, before you run 25,000 miles or two years, I would sure suggest a used oil analysis to make sure all is well in there. Blackstone sells a neat pump that can extract a sample size via the dipstick tube.