You’ve probably noticed that servicing a car is usually structured around how many miles it has traveled. This measure is baked into almost every aspect of a car’s repair schedule, with the manual describing how far it the vehicle can drive before it needs an oil change, a tire rotation and even the replacement of certain parts like belts and filters. Why use distance rather than time? Or rather, why prioritize distance over time, as most service schedules tend to do?
Miles Versus Time
When you drive your car, it produces a significant amount of heat under the hood, and over time, that heat can cause fluids and parts to simply wear out. While some commercial vehicles might actually have an engine hour monitor that tracks how long a given truck or car has been running — since idling is a big component of that type of operating environment — it’s far simpler for an automaker to keep track of how many miles have been driven than try to quantify the amount of time spent out on the road. When servicing a car, that measure is then used to calculate the likelihood of needing an oil change or some other type of maintenance.
Storage Versus Driving
Heat can also affect other parts of your vehicle like your tires. The heat generated from the friction on the road gradually wears away rubber, which is why your manual recommends rotating your tires at specific mileage intervals to even out the wear and get the longest life out of all four tires. When servicing a car it wouldn’t make sense to rotate the tires every two or three months if it hadn’t been out on the road being driven, as there would be no wear to mitigate. The same is often true of engine belts: If they haven’t been spinning in the hot under-hood environment but simply sitting in a garage, then they aren’t in any danger of wearing out.
Are There Exceptions?
On a long enough time line, servicing a car has to take into account not just mileage but also how long a certain component or fluid has been in use. While sitting for a month or two won’t have a negative impact on engine oil, for example, a vehicle that is stored for six months to a year — or which has been used only sparingly during that period — should have its oil changed to keep the additives in the lubricant fresh.
The same is true of tires, or anything else made of rubber on your car that has a regular maintenance schedule. Rubber breaks down over long periods of time, especially if it is exposed to ozone from sitting outside in the sun. Tires have a production date marked on the sidewall and must be used within a certain number of years from that time or they’re no longer considered safe. If you notice any cracking in a tire or an engine belt, that’s a surefire sign that it needs to be replaced, even if you haven’t hit the recommended mileage window to have the component serviced.
Ultimately, keeping track of your car’s mileage will help you stay on top of its service schedule.
Check out all the maintenance parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on servicing a car, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photo courtesy of Morguefile.
Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.