Yes! I prefer the heat and cool method to crisp items with higher fat content, like granola, chips, and ranch oyster crackers. All you need to do is dehydrate the moisture content from the stale items.  Heat the oven to 325 degrees F, turn it off, and then set the sheet pan of evenly spread seasoned oyster crackers in it as it cools. The oyster crackers will get hot fairly fast, so check after 4-5 minutes and stir. Most flour-based products need to cool completely before they are crisp to the bite.