You can use either old fashioned or quick oats whichever you have. Also it doesn't matter if the peaches are in heavy syrup or not because you are going to drain them.
Peach Crisp Recipe
29 oz can sliced peaches, drained
1/2 cup flour (either plain or self rising)
3/4 cup brown sugar ( light or dark)
1/2 cup oats ( quick or old fashioned)
1 stick butter softened
1 teaspoon cinnamon
Preheat oven to 400. Bake for about 20 minutes until golden.