Place the vegetable oil, garlic powder, onion powder, black pepper, ranch dressing mix, and crushed red pepper flakes in a 2-gallon plastic zipper bag. Seal the bag and smoosh with your hands to thoroughly combine the oil and spices. Place the crackers into the bag, seal, and turn the bag over to cover the crackers with the spice mix. Let the bag sit for about 1 hour, then turn again. Repeat several more times until the crackers are well-coated with spice mix, and allow the bag to sit overnight. Remove crackers and serve.