The date syrup makes it much thicker. Add more mylk if you like it thinner.
You can make your own oat mylk or almond mylk with 1 cup of oats/almonds to 3 cups of water and put through your juicer. I soak the almonds over night and then make the mylk. See mylk recipes for how to make. You can also do this in a blender too and strain with a nut mylk bag.