Just be sure to use the right grade, and don't get the cheap stuff get a good quality oil like Pennzoil or Valvoline. Your engine will pay for you going cheap!
Make sure you find quality oil from the same species of dinosaur.
long as the oil weight is the same your good to go. If your using full synthetic use the full synthetic kind.
All motor oil will mix satisfactorily.
No , it would do no harm. I think it is good to get quality oil.
no problem. use the same grade is best (ex 10w40)
i have a 2005 Nissan Murano. If I usually get oil changes at a mechanics shop, and I need to add more oil, would it hurt to mix it with stuff off the shelf?