The intervals between filter changes have been increasing: now 5,000 to 7,500 miles (or longer) for most oil filters, and anywhere from 30,000 to 60,000 (or longer) for engine air filters. With such long intervals between changes, it’s important to make sure your customers get a quality filter that will go the distance.
Back in the day when most motorists changed their oil every 3,000 miles or three months, and engines were equipped with quart-sized filters, some penny pinchers only replaced their oil filters at every other oil change. That would be asking for trouble today because filters have gotten much smaller and oil change intervals are much further apart. The oil filter must be replaced every time the oil is changed. No exceptions. What’s more, the filter should be a premium-quality, long-life (high-capacity) oil filter if a motorist is using extended oil change intervals of 7,500 miles or more.
On some vehicles with oil reminder lights, the oil change intervals can vary quite a bit depending on operating conditions. The computer keeps track of hours of engine operation, idle time, vehicle speeds and loads and operating temperatures to estimate oil life. When the oil is nearing the end of its estimated life, the oil reminder light comes on to signal the driver that it’s time for an oil change. Under ideal driving conditions, the oil reminder light may not come on for 12,000 to 15,000 miles.
Just remember that these kinds of applications, oil life is an estimated value, not the actual condition of the oil. A few vehicles use an oil-quality monitor sensor that measures the electrical resistance of the oil to determine its condition. But with the indirect systems that only estimate oil life, the calculation is often based on using a premium-quality full synthetic or semi-synthetic motor oil and premium-quality, long-life filter. If conventional motor oil or an economy filter is used in one of these applications, the oil reminder light may not be accurate, and the oil and filter should be changed according to a reasonable time/mileage schedule (say 5,000 to 7,500 miles).
As for air filters, their service life depends on how much dirt and dust they are exposed to. Driving on rural gravel roads can plug up air filters very quickly, requiring the filter to be replaced every couple of months. The condition of the filter can be determined by visually inspecting it after removing it from the air cleaner housing. Most flat panel air filters are fairly easy to inspect, but some cone-shaped and cylindrical filters can be difficult to access.
A replacement filter must fit the same as the original so no unfiltered air can leak past the filter. Something else to watch out for are poor-fitting plastic air filter housings that may have warped as a result of heat exposure. If the housing does not seal tight and hold the filter correctly, it must be replaced.
There have been reports of some poor-quality filters shedding micro fibers that contaminate the mass airflow (MAF) sensor. This can upset the engine’s air/fuel mixture, which reduces performance and fuel economy, and may cause the Check Engine light to come on.
Standard replacement filters should provide the same degree of filtration and service life as the original filter. Premium filters may offer more efficient filtration for better engine protection and/or increased filtering capacity for longer service life. There also are lower restriction performance air filters for customers who want more high-speed power.