50,000 miles, 8 years old. An average of just over 6,000 miles per year, or 17 miles per day. This in any way of thinking is low mileage. When will people learn that low mileage does not mean low engine wear? In fact low mileage means high engine wear. 75% of all engine wear occurs in the first 5 miles of any journey, when the engine is cold and combustion efficiency is poor. Oil in the air filter will be there due to engine breathing heavily. Carbon deposits due to cold engine running will cause the piston rings to gum, and cylinder compression will pass them creating a compression in the crankcase. Oil fumes will then find their way into the air filter, and eventually it will be full of oil.

In basic terms the engine is worn to some degree with all the short journeys taking their toll. You're not going to fix this easily or cheaply so the best thing is to keep it running the best way you can.....

SCZ, my point is this. Low mileage cars would've done far more short journeys than high mileage ones because it isn't possible to accumulate a lot of miles by just going to the local shops and back. There's no doubt that the best engines are found in cars that have clocked up a lot of miles in a relatively short period. Cars have internal combustion engines which work by generating and making use of heat. Railway engines give very little trouble because they are always running and clock a lot of miles. A car which is driven on a motorway everyday for a couple of hundred miles at a time will always be running at the optimum temperature, and therefore well run in. The combustion chambers will be clean due to the efficient burning of the fuel. The amount of carbon that engine produces will be kept to a minimum, and the engine oil and exhaust system will be warmed throughout. The fuel injectors (and spark plugs if it's a petrol engine) will remain in good condition, and because combustion is efficient the oxygen sensors and catalyst will also be working properly. Carbon is a by-product of combustion, and more carbon is produced by a cold engine because of combustion inefficiency. It's this carbon that causes the engine oil to blacken. Carbon is also collected by the oil filter. The filter can only hold so much carbon and eventually it will de-grade the oil and turn it to a paste, which rather than lubricate the engine's moving parts will help to wear them more quickly. Regular servicing is essential in all cases, but the manufacturers claims that the car will go X0,000 miles between services goes out the window on cars that just don't do the right kind of mileage. Emission problems and Malfunction Indicator Lamp (MIL) illuminated on the dash are far more common on low mileage cars for the reasons I've pointed out.

Hydrocarbons is the amount of unburned fuel present in the exhaust and we measure it in parts per million (PPM). Ideally this figure should be as close to zero as possible, but on cars from 2002 onwards the MOT maximum limit is 200 PPM. The higher the figure the more inefficient the combustion.

The biggest drawback with high mileage cars is the interior tends to show signs of wear where low mileage cars don't.

No internal combustion engine is ideally suited to short journeys, but I would say that a small petrol engine would be the least unsuitable. A small engine will warm up more quickly than a larger one. Regular and proper servicing does pay in the end. Electric cars have still never really happened, and I seriously doubt that they will. But they would be most suited to round the town short hops.

Diesel engines are still as dirty as they ever were, but today's emission standards require them to be much cleaner and less polluting. This can be achieved by managing the use of a 'Diesel Particulate Filter' which is a part of the exhaust system. Soot produced by combustion is collected and stored in the filter, and a process known as 'Regenerating' clears the filter under certain operating conditions. This is usually when the car is travelling at a constant speed, with the engine at normal temperature over a certain period of time. The Engine Management System monitors the pressure difference either side of the filter, and when the difference reaches a certain point then the regeneration process can by employed. This will never happen if the car is only ever used for short trips. The filter will eventually become blocked which is a problem waiting to happen, and an expensive trip to the dealer will then be necessary. So a post 2008 diesel car is not really suitable for your kind of use.