Place vegetable oil, ranch dressing mix, garlic powder, lemon pepper, and cayenne pepper in a gallon-size resealable bag; seal and gently shake to mix oil with dry ingredients. Add pretzels and seal bag; shake to thoroughly coat pretzels with seasoned oil. Let pretzels marinate in the bag for 30 minutes. Shake bag and marinate another 30 minutes. Transfer pretzels to a paper towel-lined baking sheet to dry.