The Media is the Message

Given the internal forces at work in a modern-day engine, it’s somewhat strange to think of a filter as a line of defence. Yet it’s this thin, porous material that’s responsible for protecting pistons, valves and bearings from the grinding forces of contaminants.

As similar as they may look from the outside, however, there are significant differences between leading filters and their value-priced alternatives.

“What we’ve been finding with second-line products, even a lot of the offshore stuff, is they are very limited in their dirt-holding capacity,” explains Wayne Smith, product manager for Affinia Canada’s Wix filters.

A first-line oil filter for a Ford may be rated to hold 13.93 grams of contaminants, but capacities of equivalent second-line filters have been measured at levels such as 1.33, 4.12 and 5.57 grams, Smith says, quoting his company’s research.

Once a filter is restricted, of course, the bypass valve sends unfiltered oil into the engine.

Meanwhile, the Society of Automotive Engineers’ Single Pass Efficiency Test measures how well filters block particles smaller than 20 microns in size. (These are the ones that are small enough to infiltrate bearings.) While the average oil filter runs at 90 per cent of its efficiency, some second-line products block a mere 67 per cent of the contaminants that are thrown their way, he adds.

The differences often come down to the quality of the filter media itself.

“Initially, filtration media was primarily made of cellulose fibers bonded with a resin,” says Gary Bilski, director of oil filter engineering at Honeywell, which markets FRAM filters. “Synthetic fibers were added to the cellulose to provide both higher efficiency and durability. More recently, with the advent of synthetic oils and longer change intervals, there are filter products on the market with very high levels of synthetic media and structural filter support.”

Among other differences, a synthetic filter media can feature pores with a consistent size.

But even the design of a casing can play a role in filtration.

“The filter design must be robust and able to withstand the pressure impulse cycles, vibration, and temperature extremes,” adds Bilski. “The adhesives for sealing functions and the elastomers for the anti-drainback valve and sealing gasket must be carefully selected and thoroughly tested to ensure they are compatible with the oils at both high and low temperature and have the necessary durability.”

Something as simple as a cheaper spring in the end of the can could let oil pass between the baseplate and filter in cold-weather conditions, or whenever a motorist “gooses” the throttle.

Regardless of the design, however, no filter lasts forever – customers need to be reminded to change them on schedule. Even motorists at the wheel of GM products equipped with in-dash warning lights may be blissfully unaware of the need to change a filter, since related warning lights are based on the viscosity of the oil, Smith says, noting that the readings don’t account for dirt in the filter.

Clear the air

Advancements haven’t been limited to oil filters, either. The Ford Focus, for example, includes a filtration system that can last 150,000 km, capturing dust and small particles in the medium, while letting bigger particles drop to the ground.

“Every time you open the air filter up, you’re causing dirt to get into the engine,” Smith says, referring to the growing interest in long-life designs.

Still, sealed units may not be the be-all-and-end-all in filter designs, says Erik Brown, Honeywell’s engineering manager, air filters. “Exchangeable filters allow a filter to be easily replaced more frequently, allowing a consumer to maintain their vehicle at maximum performance.”

Like their oil-filtering counterparts, air filters also rely on proper seals to ensure that contaminants are forced to pass through the filter media.

“The material for this seal must be dimensionally correct, as well as designed to withstand the vibration and temperature cycles of the engine compartment,” Brown adds.

So, too, is there a difference in the filter media itself. Second-line filters can be missing moisture barriers, Smith adds, “and you know what happens to paper when moisture hits it.”

Cabin Air Filters account for another filter design that’s becoming evermore popular among automakers – ever if they’re still an unusual commodity in the minds of many consumers.

“I think for the most part [the cabin air filter] is probably still out of mind,” admits Bruce Richardson, marketing VP for ATP Inc. “But with a filter in there, if it gets clogged up, you are going to get a decrease in air flow sooner or later.”

Most need to be replaced every one to three years, or more often in dust-filled areas, but the task is much simpler than ever. Some of the filters even incorporate carbon to control odors.

Simple installations

The installation of a filter can be one of the simplest tasks in the world of automotive repair, but it still requires proper procedures. An old air filter, for example, has to be removed with care to ensure that captured contaminants don’t simply fall into the engine.

The most common mistakes include failing to look up the correct filter number, or not checking a mounting base for any signs of defects, adds Gary Donahue, training manager, Honeywell Consumer Products Group.

Yet there are also design differences that can help shorten installation times.

K&N, for example, fixes a nut on the top of its oil filters for this purpose. “With today’s vehicles being so tight in the engine compartment, that one-inch nut becomes handy when installing or removing the filter. We’ve seen some engine compartments where you couldn’t turn a [regular] filter wrench,” says Shane Reichardt, the supplier’s public relations manager.

FRAM filters, meanwhile, include a SureGRIP no-slip finish to make the filters easier to install with oily hands.

And in cases when re-useable air filters can be cleaned, patience seems to be the over-riding virtue.

“Over-oiling is probably the biggest concern we’ve got,” Reichardt says, noting how installers should use the company’s graduated plastic squeeze bottles that ensure an even application. (Too much oil will clog the pores, and may even drip into the air box.) Simply squeeze a light amount of oil at the top of each pleat, and wait about 10 to 15 minutes for it to wick through the filter media.

It’s in the name

But in the end, the name on the box may be one of the biggest factors supporting premium filter sales.

In an earlier interview with SSGM, Ramon Nunez, vice-president of filter product management for ArvinMeritor, suggested that White Box offerings may be limited.

“Most private label programs will only carry an oil filter line, an air filter line, and possibly a fuel filter line,” he said. In comparison, the name-brand designs offer a wider catalogue accompanied by marketing materials that can be important for sales.

“When you look at low-end products … typically what you see is a much more no-frills kind of a program,” he added.

Indeed, it’s what’s inside that counts, but your shop will also need the added marketing support to help consumers make a better decision.

Caring for Reusable Air Filters

Permanent air filters require care in cleaning and oiling for long life and trouble free performance. Here are a few tips derived from FRAM’s AirHog instruction set:

* Prolonged exposure to heat or sunlight may cause the filter to dry out. If the filter appears too dry, but does not require cleaning, a light application of oil is recommended.

* Don’t saturate the filter with oil – it could be harmful to the vehicle’s air induction system.

* Don’t use gasoline, cleaning solvents, steam, caustic solutions or strong detergents to clean t
he filter. Don’t use brushes or tools, and never spray the filter with compressed air or high-pressure water. Always use slow flowing, cool water to rinse filter. Failure to follow these safeguards may result in damage to the filter media.

* Remember to inspect and clean filter housing prior to re-installing the filter.

* Tap the filter against a flat surface to remove any loose or caked-on dirt. Take care not to contaminate the clean side of the filter element.

* Place filter on a flat work surface and spray both sides of the filter liberally with air filter cleaner. Allow the solution to soak into the filter media for at least 10 minutes.

* Rinse the filter using cool, low-pressure tap water. Rinse from the clean side.

* Allow filter to completely dry naturally. Never use compressed air, heat or open flames. Heat may cause the filter media to shrink. Failure to follow these safeguards may result in damage to the filter media. It is very important that the filter media is dry prior to re-oiling.

* Use the specified oil when preparing the filter.

* Don’t over-oil. Sparingly apply filter oil to each pleat. Spray each pleat only once. Only a light covering of oil should be applied.

* Ensure that the sealing surfaces are properly seated.

* Affix the “Do Not Discard” sticker in a highly visible location on the outside of the filter housing to prevent a service technician from discarding the filter.