Motor oil is one of those essential fluids that an engine needs to operate smoothly. It lubricates crucial components, prevents wear, and also aids in cleaning and cooling the engine, ensuring it functions optimally for an extended period.
Motor oils available today are classified based on their thickness and the manufacturing process. Let’s explore how each of these factors should influence your purchasing decision.
Monograde and Multigrade Oils: What do the Numbers Mean?
A key property of motor oil is its viscosity or thickness, expressed using numbers indicating its ability to resist flow. The Society of Automotive Engineers (SAE), a U.S. organization, uses these numbers to describe oil thickness, and SAE standards have been widely adopted globally.
Originally, motor oils were of “single weight” with a single viscosity index, like SAE 30. However, this didn’t account for the fact that oil is thicker at colder temperatures before thinning out in warmer conditions.
This meant a specific car might need SAE 30-weight oil at its operating temperature, but this oil would be too thick at colder temperatures, leading to excessive engine component wear or difficulty starting the car.
Today, multigrade oils have become the norm and have addressed the aforementioned issue by using additives that allow the oil to have variable viscosity over a range of temperatures. This means that in cold conditions, the oil is fluid enough for easy starting, while its viscosity increases at higher temperatures to adequately lubricate and protect vital engine components.
Multigrade motor oil typically comes with a rating like ’10W-30′ or ‘5W-40’, with the ‘W’ in this rating standing for ‘Winter’. The first number (before the W) describes the oil’s viscosity at lower temperatures, while the last number demonstrates the oil’s viscosity at higher temperatures, up to 100°C.
While these temperatures refer to inside the engine, they can also be influenced by other environmental conditions, such as ambient temperature. Therefore, a manufacturer may specify the use of a multigrade oil with different specifications for the same car in different geographic areas.
Types of Oil: Mineral vs. Semisynthetic vs. Synthetic
Aside from viscosity, motor oil also differs based on the manufacturing process. Today, motor oil manufacturers classify their products into three categories: mineral oil, semisynthetic oil, or synthetic oil.
Mineral Oil:
- Obtained naturally from crude oil found in wells worldwide.
- Highly refined for automotive applications.
- Generally the cheapest type of motor oil.
- Suitable for entry-level cars with no focus on performance.
- May have a shorter lifespan, requiring more frequent oil changes.
- Example: Valvoline’s XLD Premium, known for protecting against sediment formation and corrosion.
Synthetic Oil:
- Man-made in a laboratory or obtained naturally but highly processed.
- Typically the most expensive type, offering the best performance in terms of longevity and lubrication.
- Preferred for sports cars and other premium vehicles.
- May contain special additives catering to specific engine types.
- Example: Castrol’s Edge, a fully synthetic motor oil.
Semisynthetic Oil:
- A blend of mineral and synthetic oil.
- Achieves some benefits of synthetic oil while maintaining a more affordable price compared to fully synthetic options.
- Example: Shell’s Helix HX7, a commonly available semisynthetic motor oil.
Understanding these distinctions in motor oil types can help you make an informed decision based on your vehicle’s needs and your budget.
