Engine oils are available to buy with a wide range of different levels of viscosity or thickness. As a rule, the engine oil that you should use in your vehicle will be dictated by its make and model and this extends to its viscosity. Therefore, to find the thickest oil you can put in your car, you should always consult the recommendation provided by its manufacturer. Read on as we explore oil thickness in greater depth and explain how to select the right option for your ride.
Understanding car engine oil viscosity
Engine oil viscosity is a term that refers to how easily an oil pours at a particular temperature. For example, thin oils will have lower viscosity and therefore pour more easily at lower temperatures than oils which are thicker and have higher viscosity levels. A thin engine oil will reduce friction between metal parts within engine’s system, but also will help engines to start quickly when the weather is cold. However, thicker oils are better at maintaining both oil pressure and film strength at higher loads and temperatures.
How to read viscosity references
The Society of Automotive Engineers (SAE) created a viscosity scale for engine oils.
Viscosity is referenced on products using the common “XW-XX” classification. The number before the “W”, which stands for winter, rates the engine oil’s flow at -17.8 degrees Celsius and the lower this number is, the less the engine oil will thicken in cold temperatures.
The numbers following the “XW” indicate engine oil flow at 100 degrees Celsius and display the oil’s resistance to becoming thin at higher temperatures.
For example, oil that has a 5W-30 grade will thicken less than engine oil that has a 10W-30 grade in colder weather. Engine oil with a 5W-30 grade will thin out more swiftly at higher temperatures compared to oils that have a 5W-40 grade.
In winter and for vehicles used in colder climates, engines benefit from using motor oil that has low winter viscosity. However, in summer and in warmer regions, an engine will benefit from oils with higher viscosity grade at 100 degrees Celsius.
Along with consulting your vehicle specifications and manufacturer recommendation, to work out the best thickness of oil for your car, always take into consideration the regional climate that your vehicle is operating in and whether it is summer or winter.