Rolled oats, old-fashioned oats, and quick oats are all fairly similar but change your crisp mixture in subtle ways. Some say the difference between a good fruit crisp and a great fruit crisp is in the oats. I think quick oats make the best crisp topping, but you can use what you have. The difference is not that big of a deal although the topping will be slightly chewier than if you used quick oats.