Filters: The clean fast movers

As they are replaced mainly at service time, filters are one of the most popular workshop fast movers. Yet, how are filters affected by car owners cutting maintenance costs? Rob Marshall provides an update.

External factors such as escalating household bills, intensifying interest rates, burgeoning inflation, rising used car values and restricted new vehicle supplies are affecting our businesses and customers. Workshop experience, coupled with real-world data, shows an increasing age of cars on UK roads. While there have always been motorists who will cut costs to almost suicidal levels, Volkswagen Financial Services found over the summer that a third of drivers have skipped essential car maintenance due to cost pressures. This echoed the results of a similar survey, from BookMyGarage.com, last December.

We asked leading OE-quality filter suppliers whether these survey results have been reflected in reality. Their responses are inconclusive. Comline says that, in the current climate, motorists tend to save money where they can. Specifically, the company has noticed that cabin filter replacement is being skipped. First Line attests that its filter sales have grown; whereas Blue Print says that its overall filtration market is flat, compared with 2022, although it has found that fuel filter sales are showing a decline, possibly due to them being, typically, more expensive than other types. LKQ Euro Car Parts, which offers multiple filter brands, confirms that its trade customers, generally, have not switched to cheaper filters. Yet, Audura, the company's entry-level brand that caters specifically for retail customers, is performing strongly.

Avoiding cutting corners

The findings from Comline and Blue Print indicate that even where servicing is taking place, certain filters are being left out to save money. The bilstein group's Blue Print brand advises that engine efficiency, fuel consumption and performance are all affected by filter quality. Ignoring, or extending, filtration replacement is a false economy and it is a good idea to warn customers if they try to shave costs by not replacing filters. First Line confirms that worn, or clogged, cabin filters can impede the performance of the heating, ventilation, and air conditioning (HVAC) system. This can even pose a safety risk, especially as the demisting facility will not work as intended. First Line advises technicians to tell customers that cabin filters should be replaced annually, at least.

When to replace filters

We think that technician experience should prioritise official manufacturer maintenance schedules. The aftermarket has known for a long time that some carmakers over-egg their service intervals, especially when biennial garage visits are stipulated. Yet, this could lead to accusations that you are making work for yourself, when you really have the customer's best interest at heart. Comline shares our view and advises that we should treat manufacturer schedules as maximum timelines. Filter change intervals depend more on the conditions in which the vehicle is driven and garages should explain the potential consequences of not changing filters either on time, or when it is needed. For instance, over many years of seeing how cars perform as they age, many aftermarket professionals, who are not beholden to manufacturer schedules, advise that diesel fuel filters, oil filters (along with the engine oil) and cabin/pollen filters are renewed every year.

Are you the problem?

It would be easy to say that fitting new filters is so easy that even apprentices could do it but it appears that even seasoned professionals are making basic mistakes. Even air filters can be fitted carelessly, so that the edges do not make a satisfactory seal against the air filter box. Not only can this cause running issues but it can also create a hissing noise, especially under acceleration. Comline reports that it still sees cabin/pollen filters being installed the wrong way around, where the airflow direction arrows are not noted. When replacing diesel filters, Blue Print advises that technicians pay special attention to the bleeding procedure to help avoid serious damage to the high-pressure diesel pump that relies on the fuel for its lubrication. The biggest issue is down to overtightening and cracking fuel and oil filter element housings. This explains the importance of heeding the torque values, which some manufacturers print on the cap. Furthermore, as these composite housings are relatively delicate, improvisation attempts with incorrect tools are likely to damage them.

Use a torque wrench, when refitting plastic filter housing caps

Specialist filters

While we have considered only conventional fuel, air pollen/ cabin and oil filters, Blue Print says that technicians should also consider specialist filtration needs, including those fitted to rear-mounted All Wheel Drive Haldex filters and transmissions. Through its febi brand, the bilstein group sells complete transmission oil and filter kits for over 8,000 applications, which is worth considering when dirty oil and blocked filters have been the death knell for many automatic and twin-clutch gearboxes. The company is expanding its range to include rear differential couplings, so expect a range of Haldex Oil and filter kits to appear under the Blue Print banner, shortly.

The diesel fuel filter (pictured right) was filthy, after being in place for only a year. Had the manufacturer's schedule been followed, it would have been left for a further twelve months

Do not forget filter upgrades, too. While cabin/pollen filters provide upgrade opportunities, keep abreast of the latest products that you can consider to bolster your revenue. For instance, clogged high-voltage battery filters cause cooling issues. An upgrade that you can make to certain Toyota Prius (ZVW30 & ZVW35) models is fitting an air filter (Blue Print part number ADBP250046) to prevent the cooling fan from becoming blocked with interior dust. This issue causes the high-voltage battery to overheat and create P0A82, or P0A84 fault codes. This modification is especially worthwhile for taxi driver customers.

Latest updates

To celebrate its sixth year in the UK, UFI Filters has introduced a range of Heavy Duty filters to the UK and Ireland. Through its UK warehouse and partnership with Parcelforce, UFI has sought to enhance its already high service level, by offering a next-day delivery service. Meanwhile, both Comline and First Line are expanding their EV cabin filter offerings. For instance, over 72 new part numbers have been added to the Blue Print portfolio, including those for Chinese manufacturers, MG and Maxus, as these brands become more popular on UK roads.