Preheat the oven to 250°F. Line two rimmed baking sheets with parchment paper.
In a large GIANT bowl, combine the Chex cereals, pretzels, bugles, cashews, Cheerios, and Cheez-its.
In a measuring cup, whisk together the ranch seasoning, dried dill, garlic powder, and oil. Drizzle the ranch mixture over the cereals in stages, mixing well with your hands or a large spatula until everything is evenly coated.
Divide the mixture in half and spread over the two baking sheets. Bake for 45 minutes, stirring every 15 minutes, until the mixture is light golden brown. Cool for a few minutes before serving.
Store in an airtight container for up to 2-3 weeks at room temperature.