Final answer:
Before a long road trip or monthly, you should check the oil level, tire pressure, and coolant level in your car to ensure safety and vehicle efficiency.
Step-by-step explanation:
Once every month, or before you go on a long road trip, you should perform routine checks on your vehicle. This includes checking the oil level and topping it up if necessary to ensure the engine runs smoothly. Additionally, you should also check the tire pressure and inflate the tires if needed, which is crucial for maintaining a smooth and safe ride, improving gas mileage, and reducing tire wear. Finally, checking the coolant level and adding more if it is low is important for preventing overheating and potential engine damage. Hence, the correct answer is 4) All of the above.