Knowing Your Filters

Knowing Your Filters

Whether you want maximum fuel efficiency from your engine (who doesn’t?) or suffer from persistent allergies, understanding the different filters on your vehicle can save you time, money, and headaches.

Every modern car has four main filters: the oil filter, air filter, cabin filter and fuel filter. In their own way each of them is a high performing and critical part of your vehicle. Not changing filters on time can cause engine failure, poor fuel economy, and even respiratory issues for you and your passengers.

Oil Filter

Oil Filters

The oil filter maintains continuous oil flow and purifies engine oil by removing deposits (contaminants, carbon, metal particles etc) so that the oil can do its job efficiently.

Often described as the lifeblood of your engine, oil does a number of very important things. It cools the engine by dissipating heat, absorbs contaminants and safely holds them in suspension, and lubricates the engine to reduce friction and prevent wear.

Fortunately, advances in modern engine oil and filter technology means that today’s cars can go twice or even three times as long before needing an oil and filter change than those of our Fathers or Grandfathers. However, that’s only true if certain rules are followed:

  1. A high quality fully synthetic engine oil is used
  2. A high-quality oil filter is used
  3. The vehicle isn’t only used for short distance stop-start trips
  4. The vehicle runs on high quality, low-sulphur fuel
  5. The vehicle has a history of regular, on-time oil changes

If several or all of the above aren’t true for your vehicle, more frequent oil changes are recommended to avoid serious and expensive problems in the future.

Over time, oil becomes saturated with engine and fuel deposits and will eventually turn ‘gritty’ or ‘sludgy’. Your oil filter collects these deposits to prevent them from travelling around the oil system and forming up in critical areas of your engine, but only for a limited amount of time. If an oil and filter change is extended or missed altogether, these deposits will dry out and harden. This sludge can block the narrow oilways and galleries that ensure the thorough distribution of oil around your engine and will cause excessive heat, friction wear and eventually engine failure due to the oil starvation of critical engine components.

Oil filters are generally cylinder shaped. The outer case is made of thin metal and inside there’s a pleated, fibrous filter which is the part that traps the oil deposits. At the bottom of the filter is a metal gauze that allows the oil to flow into the filter and back out again under pressure.

The oil filter should be changed every time your oil is changed. A new oil filter will keep your new oil cleaner for longer.

At John Dale Motors we only use the very highest quality oil and oil filters specific to your vehicle. Using cheap or the wrong type of filter for your vehicle can cause oil leaks, low oil pressure, high oil pressure, and damage to engine components from wear and overheating.

Air Filter

Air Filters

The humble air filter is another very important part of your vehicle. It stops debris and other contaminants from getting into your engine and causing damage.

Your car’s engine runs on a combination of fuel and air (it needs the oxygen). This mixture is ignited inside the engine and the resultant combustion creates the momentum that moves your car along. In basic mechanics, your car’s engine operates because of Suck (Air Intake), Squeeze (Compression), Bang (Combustion) and Blow (Exhaust).

The air drawn into your engine by the air intake contains the same particles as all air, namely sand, dust, debris, grit, pollen, and soot. None of these particles are welcome in the air/fuel mixture, so the job of the air filter is to trap these particles and prevent them from entering your engine. Over time, the air filter becomes increasingly more clogged, which can lead to poor fuel economy and poor performance. An engine that breathes better will perform better.

The recommended replacement interval for your vehicle’s air filter is set by your vehicle manufacturer, but several environmental conditions, particularly for most Australians who live on the coast where sand, dust and grit are more common, can severely reduce the recommended time or kilometres interval for air filters.

An unexpected drop in fuel economy, lack of power, starting problems, rough idling or a dashboard warning light coming on can all be signs that your vehicle’s air filter needs replacing.

Air filters come in various shapes and sizes specific to each vehicle type. They can be made of pleated paper, cotton, or synthetic materials. Some are rectangular, some are cylindrical or round, and they’re generally built into a plastic or rubber frame. When it’s time for a new one, both the filter and frame get replaced as a complete unit.

At John Dale Motors, our expert team inspects and replaces the correct air filter for your vehicle using the highest quality brands available to maintain optimum engine performance and fuel efficiency.

Cabin Filter

Cabin Air Filters

Now for the filter that many motorists don’t even know exists in their car and it’s one of the most important – the cabin air filter.

The cabin air filter, or ‘pollen filter’ is different to the engine air filter we’ve just talked about. Whereas the job of the engine air filter is to filter the air entering your engine, the job of the cabin air filter is to clean the air entering your vehicle’s passenger cabin.

The cabin air filter sits in the ducting of your HVAC (Heating Ventilation and Air Conditioning) system. Sometimes they are in a convenient position such as behind the glovebox but can be in a more difficult to reach position such as behind the dashboard. The cabin air filter filters out bacteria, dust, pollen, and other harmful airborne contaminants from the airflow that enters your vehicle’s cabin. If your cabin filter is carbon activated, it also captures exhaust gasses, diesel soot particulates and unpleasant odours.

Having fresh, clean air in your passenger compartment is particularly important if you suffer from asthma, headaches, allergies such as hay fever, or regularly carry children in the car.

Cabin air filters will trap particles as small as 0.0003 mm. An airborne droplet from a cough or sneeze is about 0.0005 mm and pollen is between 0.1 and 1.0 mm. Basically, a cabin air filter in good condition will trap almost every airborne particle!

As with any filter, a cabin filter will become increasingly blocked with the particles it has trapped over time, meaning it loses its ability to pass clean, filtered air into the cabin. This can cause reduced efficiency of your vehicle’s heating and air conditioning system, making it work harder to cool the cabin or demist the windows. A blocked cabin filter also reduces the amount of fresh oxygen reaching the passenger cabin – particularly dangerous on long journeys, as a lack of oxygen decreases your awareness and increases your tiredness and fatigue.

Cabin air filters should generally be replaced every 10,000 kms or once a year. However, if you live in a dusty, sandy area, suffer from asthma and allergies, or you have noticed stale or mouldy smells in your passenger cabin it should be replaced more often.

Fuel Filter

Fuel Filters

The primary function of a fuel filter is to filter out impurities from the fuel. By doing so, a wide range of troublesome performance and drivability issues can be avoided. These impurities include grit, rust, sediment from the fuel tank, water, and varnish deposits. Combined, they can have an abrasive action, speeding up wear and tear to expensive parts such as fuel pumps and injectors. Fuel debris is unwanted in older carburettor engines, but modern fuel injection and electronic vehicle management systems are very high precision and even more sensitive to these deposits entering the fuel system and combustion process.

The fuel filter can be located in a variety of places depending on the type of vehicle. It might be in the fuel tank itself or positioned underneath the vehicle on the chassis along the fuel line. Many vehicles even have one of each.

As the fuel filter plays such an important role in keeping the fuel clean and flowing correctly, it is important to replace them at the recommended intervals or whenever you suspect your vehicle may require maintenance. Some of the signs of a clogged fuel filter include starting problems, poor idling, lack of power, or engine cutting out.

Older vehicles, or those used infrequently need more regular fuel filter replacement, but just one tank of bad fuel can also cause any of these symptoms and require a new fuel filter asap.

Replacing the fuel filter should be left to a highly skilled professional technician, as the process involves safely disconnecting the battery and depressurising the fuel system, before fitting a new filter and checking it and the fuel lines for leaks.

At John Dale Motors, our expert team will advise you if your fuel filter needs routine replacement as part of a service or accurately diagnose whether the cause of your running problem is fuel filter related or due to a wider issue.

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The team at John Dale Motors Charmhaven are proud of our reputation for technical excellence and outstanding customer service on the New South Wales Central Coast. We look forward to welcoming you.

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Delivering expert car servicing and repairs for most makes and models, combined with outstanding customer service to motorists in Charmhaven and throughout the Central Coast.


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(02) 4392 1327

4 Botham Close, Charmhaven 2263

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