Whilst I was opening up the oil fill cap, I discovered what infrequent servicing and neglect looks like:

The black, solid looking substance which is clinging to the oil cap and top of the fill hole to the motor is oil sludge.  



This shot of the head of the motor shows the extent of how much sludge has infiltrated the crevasses of the motor.  

Its obvious that the previous owner has neglected to service the car and that the oil that was previously in there has become contaminated with engine metals, acids and air humidity, transforming it into sludge.  This oily sludge is solid and hard to clean, which in turn can clog up vital passageways in your engine if not removed.

So, remember to change your oil frequently, sticking to the factory service recommendations at a minimum otherwise you run the risk of sludging up your motor and damaging it!