Make sure your seat is exactly the way you want it, and feel free to play with any of these controls up here. I have no idea what they do. But I want mi car to be su car.
So within these back-to-back scenes, we have clear indications that su was sometimes pronounced as shoo, and sutur was sometimes pronounced as shooter.
Other documents show similar spellings of words beginning with su, and some writers in the late 1500s and 1600s even commented about that type of pronunciation.