Engine oil

Engine oil functions

The main functions of oil in your vehicle engine:

• Oil is a lubricant. Oil reduces friction and wear that occurs when parts move against each other, for example between the cylinder liner and piston ring, or the camshaft.
• Assists in heat dispersion. Engine oil absorbs the heat produced in the engine combustion chambers and piston under crown area, cooling the engine and helping to prevent overheating.
• As a sealant. Motor oil seals the space between the piston ring and the cylinder liner to prevent combustion pressure and engine power from escaping.
• Oil is also a detergent. It prevents waste matter resulting from combustion and impurities produced by oxidation from sticking to the engine interior, helping to keep it clean and last longer.
• Motor oil is also a rust inhibitor. It neutralises acids produced by combustion gases, preventing rusting, corrosion and damage to essential components.

Oil maintenance tips

1. Engine oil level should be regularly checked regardless of vehicle age.
2. Only top up oil with correct grade as specified by manufacturer.
3. When topping up oil do not exceed the maximum recommend level.

An engine is made up of a large number of important moving parts, such as pistons, crankshaft, valves and the camshaft to name a few. Engine oil plays several important roles in ensuring that these all work together properly.

Good quality engine oil will protect your engine by minimising wear and preventing sludge build up. A good quality engine oil is one that is made to an industry standard and meets the needs of the lubrication system when the engine is hot, when it is cold and under various road conditions. This is a complex problem because as the engine heats up the oil thins out and oil that has the right viscosity when cold may be too thin when hot and vice versa. Viscosity is a measure of the resistance of oil to flow and gives an indication of how the oil will perform at different temperatures.

Most vehicle manufacturers recommend multi-grade oils for their engines as they perform well within a broad temperature band. All good oils have additives to keep the engine clean, intensily resist oxidation and neutralise acidic combustion products.

• Oils have an SAE (Society of Automotive Engineers) rating for viscosity, for example 20w-50 or 15w-40.
• Oils have an API (American Petroleum Institute) rating for service applications, for example SF, SG or SH are for petrol engines and CD for diesel engines.

Your owners handbook will tell you the correct oil rating for your vehicle, you can use a higher rating oil if you wish.

Engine oil needs to be changed on a regular basis because it deteriorates, the additives become depleted, sludge begins to build in your engine and wear increases. Change your engine oil and filter at the interval recommended by the vehicle manufacturer in your owners handbook.

Check your owner's handbook for the correct oil recommendation for your vehicle.

Use a good quality oil from one of the major manufacturers that meets or exceeds the vehicle manufacturers viscosity rating and service rating.