According to US Department of Transportation studies: Cooling system failure is the #1 cause of mechanical breakdown on America’s highways. Replacing a clogged air filter can improve your car’s gas mileage by as much as 10 percent. Most auto manufacturers recommend : Changing the oil and oil filter in a vehicle every 3 months or 3000 miles. Servicing your transmission every 2 years or 30,000 miles. Professionally washing your vehicle weekly. Maintaining proper tire inflation pressure to reduce tire wear.