Air filter advice
Ideally, the engine needs as much air as possible to allow it to run efficiently. The air filter is put into the intake because, when travelling at high speed, small particles of dirt and debris cause wear in the engine intake system. A partially blocked air filter may be more effective as a filter, but this will not allow a full flow of air into the manifold, thus effectively creating a richer mixture. Modern fuel injection vehicles will suffer less from this restriction than earlier carburetted cars, but the principal still applies. From my experience, town driving will result in the quicker blocking of an air filter than regular motorway driving.
The replacement interval on the VAG data I have states that the air filter on all VAG vehicles should be replaced at intervals of four years or 60,000Km (37,000 miles). Personally, I would never leave an air filter in place longer than 30,000 miles, neither would I recommend trying to clean a paper element filter using a damp cloth as this may cause I have a four-year-old Octavia VRS CR diesel. I have recently changed my oil and filter, along with the timing belt kit, water pump and coolant at 65,000 miles. I would like to keep my engine running as long as possible, so I practice preventive maintenance.
I use Bosch air filters and have replaced my latest one after 9000 miles, my last annual mileage. However, my previous filter, which had done 18,000 miles, wasn’t dirty, just slightly coloured and certainly not black. I have vacuumed and wiped it clean with a very slightly damp sponge. I do believe in changing them earlier than Skoda’s recommendation of six years or 60,000 miles, but I am not comfortable changing them prematurely just for the sake of it.
I have read that a slightly dirty filter is more effective than a brand-new one. I have previously replaced air filters at 37,000 miles and I thought the filter was a little too much on the dirty side. I am settling on a schedule of two years/24,000 miles. Is this false economy and is this too high, or should I replace at 12,000, 15,000 or 20,000 miles? I am not in a city or a dusty countryside region, just a small town with occasional bypass/motorway runs, but mostly making short journeys. Scott Taylor
small particles of debris within the filter element to soak into the fabric, causing a greater resistance for the passing airflow.
To summarise, I think your replacement interval of two years or 24,000 miles would be a perfect compromise to protect the engine, without prematurely replacing an air filter that would still have a long life left in it.