Motor Oil lubrication is essential for cooling vital engine components, reducing friction and preventing wear by forming a thin oil film on crankshaft bearing surfaces that separates moving parts so they don’t come into direct contact. The oil film behaves like a shock absorber that cushions moving and rotating parts inside the engine. Motor oil reduces rust and corrosion inside the engine as well as helps keep surfaces clean by dissolving and carrying dirt deposits to the oil filter

Viscosity is defined as the oil's resistance to flow or the speed of its flow. The thicker the oil the slower it will flow (higher viscosity). Thinner oils (lower Viscosity) have a water-like consistency and pour more easily at low temperatures, while heavier thicker oils have more of a honey-like consistency.

Additives can alter the way oil behaves at low and high temperatures and multi-grade oils have a wide viscosity range across different temperatures. Take 5W30 for instance;

‘W’ stands for winter which is why the first number of the grade followed by the ‘W’ describes the viscosity of the oil at a low temperature. While the second number (in this case 30) describes the thickness of the oil at engine running temperature (around 100°C)

Multi-grade oils are designed to flow well at low temperatures and be able to adequately lubricate the engine at a cold start while also maintaining thickness and lubricant film strength at hot temperature. If the oil is too thin at the hot temperature it may not protect the engine effectively or if its too thick, the engine may not run efficiently. The correct viscosity grade will be indicated on your vehicle service manual.

Many vehicle manufacturers recommend using 5W30 motor oil for year-round driving. Other manufacturers specify 10W40 or 0W20. It is best to always refer to your service manual for correct viscosity recommendation. Sometimes the viscosity recommended for your car is indicated on the oil filler cap or dipstick. However, As the mileage of any car adds up there will be increased wear of internal engine bearing clearances, in this case it may be applicable to switch to a slightly higher viscosity grade to prolong engine life, reduce fuel consumption and noise; for example, if a vehicle manufacturer usually recommends 5W30 for a car that now has 100,000 miles it may be wise to either use 10W30 or 10W40 to provide better lubrication and protection. We can also help you choose the correct oil viscosity by entering your car registration number into our oil recommender.