1In an oval 5- to 6-quart slow cooker, stir together 3 cereals, pretzels, cheese crackers, bacon bits and Parmesan cheese.
2In small bowl, beat melted butter, oil and ranch dressing mix with whisk until well combined. Pour over cereal mixture; stir until evenly coated.
3Cook uncovered on High heat setting 2 hours, stirring every 15 to 20 minutes.
4Spread cereal mixture on ungreased cookie sheet or sheet of waxed paper. Cool 3 to 5 minutes before serving.