Line two large (13 × 18‑inch) rimmed baking trays with parchment paper and set aside.
Place all 18 ounces oyster crackers in a large mixing bowl.
In a 2‑cup measuring cup (or similar container with a pour spout), add 1⅔ cups canola oil, 1 ounce Ranch seasoning mix, 1½ teaspoons garlic powder, 1½ teaspoons onion powder, ½ teaspoon black pepper, and 2 tablespoons red pepper flakes. Stir very well until the oil and seasonings are thoroughly blended.
Pour the seasoned oil evenly over the oyster crackers in the mixing bowl.
Gently toss or fold the crackers to coat them evenly with the seasoned oil, taking care not to crush them.
Every 5–6 minutes, gently toss the crackers again to redistribute the oil. Continue this for about 30 minutes, or until you no longer see oil pooling on the bottom of the bowl and the crackers appear evenly coated and starting to absorb the oil.
Transfer the seasoned crackers to the two prepared rimmed sheet trays, dividing them evenly and spreading them into a single layer.
Leave the crackers uncovered on the counter to dry for about 4 hours, or up to overnight, until they are no longer wet to the touch from the oil.
Once fully dry, transfer the firecrackers to a sealed plastic container for storage.
Notes
9. Once fully dry, transfer the firecrackers to a sealed plastic container for storage.