There's "nothing worth clicking on" for question 1 because it's arguably (certainly so in my opinion) a worthless question. Without at the very least providing the specific model of car, even an experienced mechanic will struggle to answer it for you meaningfully as phrased - there are a huge range of recommended oil service intervals across different car models.
While I don't know much about cleaning windows, providing more specific context for example 2 will likely do wonders to the quality of result returned too.