Engines work through the process of burning fuels such as petrol. As a result, non-combustible by-products such as residual gases and soot are produced. Engine oil captures and prevents these impurities from coagulating inside the engine and works to keep it clean, but as it does this, its effectiveness diminishes. The effects of combustion heat and oxygen in the air can also cause engine oil itself to deteriorate, and therefore, it is essential that the oil be replaced after a period of use
Continuing to use engine oil past the manufacturer’s recommended drain interval can cause a build-up of sludge, which could inhibit piston ring movement and in the worst case can cause the oil to become sticky and tar-like, leading to engine trouble. Replacing the oil flushes out the dirt, impurities, water and other particles that adversely affect the engine. To protect your engine and keep it running smoothly, it is advisable to change your oil on a regular basis. The recommended time frame for a semi-synthetic oil is usually every 6 months or 10,000 klm which ever occurs first and a full synthetic oil 12months or 15,000km. In high performance and modified cars, this can be reduced to 3 months or 5,000 klm.