Common myths about filters

A myth: a widely held but false belief or idea. Myths are normally spread quickly, born away from what is actually real and can pretend to give the listener or reader some hidden information which goes against accepted common knowledge.

The automotive market also houses tall-tales; most unsurprisingly there are a few filtration myths which have spread around the industry, trying to explain why all filters are the same, regardless of price.

Here we go through 5 of the most common and tell you why they are just myths.

MYTH 1: The same paper is often used both in cheap filters and expensive ones.

It is true that there are a limited number of filter material manufacturers but the origin of the paper tells you nothing about its quality nor the efficiency of the filter.

There are so many other factors that have a significant effect on the quality of the filter media:

  • impregnation of the filter media
  • improvement through the use of activated carbon or nano fibers, for example
  • type and quantity of the synthetic fiber added to the paper pulp
  • composition of the synthetic raw materials used in production
  • drying time and temperature
  • production processing (pleating, curing using heat)
MANN filters pick the right medium for the job while other have a few standard media

MANN filters pick the right medium for the job while other have a few standard media

MYTH 2: Instead of buying a new cabin filter, all you need to do is brush the old one until it is clean.

If you take water and brush to a cabin filter, it will look cleaner, but the tiny particles, such as pollen, fungus or mould spores cannot simply brushed away. The cleaning process may in fact loosen them so that they enter the passenger compartment next time the ventilation system is operated.

Other problems also often occur:

  • misting of the windows (icing in winter), because residual moisture from washing the filter can enter the passenger compartment
  • recurring misting of the windows in damp weather, because particles retained in the filter material do not allow the fresh air to pass through freely
  • reduced cooling effect, because residual dirt particles can block the air flow from the air conditioning system into the passenger compartment
  • pollen, dust and dirt particles can no longer be retained, because the electrostatic charge of the filter has been lost due to washing

MYTH 3: Unlike with oil filters, the quality of air filters is not an issue – they are more or less all the same and are not as important for the running of the car.

The importance of the air filter has increased enormously in modern vehicles.

Reasons why you shouldn’t skimp on this:

  • modern engines are becoming increasingly efficient and are therefore making ever higher demands on air filters
  • with the increase in the air volume passing through the filter, both the load on the air filter and its importance have risen proportionately
  • an efficient air filter is the basis for optimum fuel combustion
  • if water enters the air filter housing (as a result of heavy rain, for example), the correct function of simple air filters can no longer be guaranteed, which leads to a drop in engine power

    A quality MANN air filter with water ingress compared to a lower quality filter

  • a flame-retardant impregnation protects both engine and occupants

MYTH 4: If I do not keep my car for very long, I do not need to buy more expensive air filters.

Costs and risks arise at all times for both driver and vehicle, even if the latter is only kept for a short time. Reasons why you should avoid cheap filters – even if you want to sell your car in the near future:

  • cheap air filters can damage the air mass flow meter sensor, which can soon lead to faulty injection behaviour, considerable loss of power and higher exhaust emissions
  • cheaper materials can cause leaking due to brittleness and poor fit. This can cause incorrect messages to the on-board electronics, which often cause considerable damage – and costs
  • the absence of flame-retardant is dangerous: The ember of a cigarette in contact with the filter medium could cause a fire

Imagine you had to change your airbag regularly. Would you then opt for a cheap model of lower quality and hope that nothing happens? Certainly not.

MYTH 5: Provided that size and thread match, oil filters are interchangeable. Therefore, you do not have to go to the effort of buying a filter with corresponding part number.

Even if the dimensions of a filter are right, it does not mean it is a good choice. From the outside, the black can may make you feel confident about what you are buying, but only a high quality oil filter offers optimum protection.

It’s what’s inside: the inner life of a quality oil filter and a cheap product

It’s what’s inside: the inner life of a quality oil filter and a cheap product

It’s what’s inside that counts:

  • the filter material must be suitable for the engine and application
  • only the right filter that matches the application perfectly is able to retain separated dirt particles until the next change is due
  • depending on the type of engine, a filter needs a certain number of valves for optimum protection against engine wear. And not only is the number of valves important, but also the correct design values, such as the opening and closing pressure of a valve, for example
  • thanks to the robust construction of the threaded cap, reliable seals and a pressure resistant, corrosion-protected housing, MANN-FILTER filters offer optimum stability and leak-tightness

For more filtration myths, have a look at leading filtration supplier MANN-FILTERS guide to the ‘10 myths about filters’.