5W-30 engine oil

The letters and numbers ‘5W-30’ tell you how this oil operates at cold and warm temperatures. The ‘W’ stands for ‘winter’ and signifies that this oil will flow as a 5-weight at engine start-up or in colder temperatures. The number 30 signifies the oil’s viscosity at 100°C, which is the normal operating temperature of most vehicle engines. Environments are often a deciding factor when choosing an oil type. For instance, 5W-30 vs 0W-30 means that 0W-30 is better suited to colder environments, but 5W-30 performs well in all temperatures. This is why it is the most popular engine oil available. 

5W-30 oil protects your vehicle’s engine, increases fuel efficiency and offers superior performance in hot and cold temperatures. There are three types of Castrol 5W-30 oil – EDGE, MAGNATEC and GTX. Try the Castrol product finder using your vehicle’s details to see which of our 5W-30 oils are best suited to your vehicle’s specifications. 

5W-30 oil can be used in petrol and diesel engines in most cars, motorcycles, trucks and SUVs. If your vehicle is often used for long journeys carrying heavy loads, consider exploring a different oil category better suited to your vehicle’s specific needs. 

• FULLY SYNTHETIC: These oils still have a mineral base but are formulated with performance-enhancing additives. The additives make the oil more chemically stable and less likely to acidify or oxidise, preventing rust and corrosion from damaging your engine. Alongside performance, fully synthetic oil has a longer lifespan than semi-synthetic, offering longer periods between oil changes.
• SEMI-SYNTHETIC: 5W-30 semi-synthetic oils are cheaper than fully-synthetic variants because they contain fewer additives. Semi-synthetic oils still work to improve engine maintenance and performance, but more and more manufacturers today recommend fully synthetic oils for the added benefits their formula contains. 

Engine grades refer to the viscosity (thickness) of the oil and the temperature it performs best. 5W-30 is the most popular engine oil because of its ability to flow easily under different temperatures – both hot and cold. You can find the fundamental differences between 5W-30 and other engine oil categories below, so you can select the one that’s best for your driving style and vehicle’s needs. 

• 5W-30 vs 5W-40 - these two oils can handle operating at low temperatures in the same way because they are both categorised using ‘5W’. 5W-40 oil is slightly better at operating in higher temperatures due to the increased ‘40’ classification.
• 5W-30 vs 0W-30 - the key difference is the weight of these two oils. 0W-30 oil is designed to flow at a lighter weight in cold temperatures compared to 5W-30, which has a higher viscosity in colder climates. Weight is important because temperatures affect an oil’s viscosity, hindering or helping to lubricate important engine components. 
• 5W-30 vs 0W-20 - as mentioned above, the difference between 5W-30 oil and 0W-20 oil is simply the oil’s viscosity. 0W-20 will flow at a 0-weight at start-up and a 20-weight when the engine runs at its optimum temperature. 5W30 will flow at a 5-weight at start-up and a 30-weight when the engine is running at max temperature. 
• 5W-30 vs 10W-40 - while offering the same benefits as all of the above oils, 10W-40 oil has additional benefits for older vehicles and motorcycles of 2-cycle and 4-cycle design. Motorbikes and mopeds have smaller engine components – similar to older car models. 10W-40 oil ensures the liquid can easily move through constricted pipes, even at colder temperatures.