How to Understand Engine Oil Ratings Like 5W-30: A Simple Guide
Engines can consist of various metals such as iron, aluminium, steel, magnesium, titanium, and several others. That is why it is vital to use engine oils that are suited to your vehicle. Pouring a randomly selected oil into your engine may not provide it with the protection it needs to work efficiently. There are reasons for this.
There are basically three types of engine oils: Mineral, Synthetic and Semi-Synthetic oils. Each type is formulated for various performance demands, protection and budget requirements. For newer engines, it would be wise to choose synthetic oil despite them being more expensive.
Besides how they are made, there’s another factor to consider: viscosity. Engine oils come in various viscosity ratings to cope with demands of the respective engines. The Society of Automotive Engineers (SAE) developed a rating system to gauge the thickness of oil.
Understanding Viscosity
Viscosity refers to a fluid’s resistance to flow. Oil with a lower viscosity is thinner and has a better flow. The higher the viscosity, the thicker the oil and the more resistance it exhibits to flow. Engine oils have varying viscosities when cold and when heated to normal engine operating temperatures.
Multigrade viscosity engine oils change in viscosity due to temperature, hence the modern rating system such as 5W-30. The number on either side of the dash describes viscosity in the cold and when operating at normal engine temperatures.
Thinner oils may be preferable during a cold start because they need less time to reach vital components such as ones in turbochargers. Thicker oils take more time to circulate throughout the engine, but may offer better protection for the engine, hence the multi-grade viscosity system.
Making Sense Of The Oil Rating System
An engine oil’s SAE rating shows how viscous it is in cold conditions as well as when heated up. An example of such a rating is 5W-30. The first number ‘5’ denotes the viscosity rating when cold, the W stands for Winter. Together, they show how viscous the oil is in the cold/winter. The lower the first number, the thinner it is during a cold start.
The second number ‘30’ denotes the oil’s thickness at the engine’s operating temperature. The higher the second number, the thicker it is when it flows through a hot engine. A 5W-30 and a 5W-40 behave the same in the cold but the latter will be thicker when heated up. The same applies for a 0W-30 and a 5W-30 oil.
Importance Of Sticking To Approved Engine Oils
Each engine has its own requirements in terms of lubrication, corrosion protection and heat dissipation. Manufacturers thoroughly test their engine requirements before putting them in production.
Efficiency and reliability are of paramount importance, which is they will select the oil that meets these expectations. Using unapproved oils which have not been tested with a particular engine may not offer the desired lubrication and protection needed.
