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Engine Oil Types Explained: Which is Best for My Car?

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motor oil types explained

Maintaining your vehicle involves a myriad of routine checks and balances, but few are as significant as the type of engine oil you use. With a plethora of engine oils available in the market, choosing the ideal one for your car can seem like navigating through a maze.

This article aims to demystify the different engine oil types and guide you toward making an informed decision for your vehicle. Understanding which motor oil to get for your vehicle isn’t always easy, but we’ll help educate you as much as possible.

Why is Engine Oil Essential?

Before we delve into the types of engine oil, it’s crucial to comprehend why motor oil is indispensable for your car’s health.

Engine oil serves several pivotal functions:

  • Lubrication: It creates a thin layer between the engine’s moving parts, minimizing friction and preventing wear and tear. This ensures a smooth, efficient operation and extends your engine’s life.
  • Cooling: It absorbs and dissipates heat generated from the friction of moving parts, preventing overheating and possible damage.
  • Cleaning: Engine oil has detergents and dispersants that pick up dust, dirt, and other particles, thus keeping your engine clean and ensuring optimal performance.
  • Sealing: It helps seal gaps between the piston rings and cylinder walls, ensuring maximum compression and preventing the escape of combustion gases.
  • Rust and Corrosion Prevention: It forms a protective layer over the engine’s metal parts, shielding them from, you guessed it, rust and corrosion.

Now, let’s delve into the different types of engine oils and their unique properties.

Conventional (Mineral) Oil

Conventional (Mineral) Oil

Conventional or mineral oil is a petroleum-based product derived from crude oil. Without being too sciency, this means it has some byproducts in it. Being the oldest type of engine oil, it is often the default choice for many car owners due to its affordability. It provides satisfactory lubrication and protection for a wide range of engines, particularly older ones.

However, conventional oil has its limitations. It tends to break down under high temperatures, resulting in a loss of viscosity and lubrication. Moreover, it doesn’t perform as well in cold temperatures, potentially leading to inadequate lubrication at start-up. This means it may require more frequent changes than synthetic oil, especially if your vehicle often operates under severe driving conditions like heavy loads or high temperatures.

There are a lot of potential trade-offs for the affordability and overall ease of using conventional oil:

  • Less chemically stable (affects viscosity)
  • Oxidize and acidify more easily (damages engine)
  • Quicker to break down and lose protective qualities (forced to replace more often)

That being said, you won’t destroy your vehicle by using a reliable conventional oil product. You can find many good conventional motor oil brands, including:

  • Pennzoil
  • Castrol
  • Valvoline

Synthetic Oil

Synthetic oil, as the name suggests, is artificial. It is chemically engineered to provide superior performance characteristics compared to conventional oil. Synthetic oil is designed at the molecular level to have consistent size and shape, resulting in superior lubrication, less friction, and better engine performance.

Synthetic oil excels in extreme temperatures. It maintains a steady viscosity in cold temperatures, ensuring excellent flow during cold starts and providing immediate protection. Synthetic oil resists thermal breakdown in high-temperature operations much better than conventional oil.

Additionally, synthetic oil provides better engine protection and cleanliness. Its advanced detergents effectively remove engine deposits and keep the engine clean. It also has longer drain intervals due to its enhanced oxidative stability. However, all these benefits come at a higher cost, making synthetic oil the most expensive option.

Synthetic Blend Oil

Synthetic Blend Oil

Synthetic blend oil strikes a balance between conventional and synthetic oil. It’s a mix designed to offer better protection and performance than conventional oil and comes with a more modest price tag compared to fully synthetic oil.

This type of oil is particularly beneficial in severe driving conditions, such as frequent stop-and-go driving, heavy towing, or extreme temperatures. It offers improved resistance to oxidation and better low-temperature properties than conventional oil. If you’re mindful of cost but want some benefits of synthetic oil, a synthetic blend could be a suitable choice.

High-Mileage Oil

High-Mileage Oil

As vehicles age and accumulate miles, their engines’ requirements evolve. High-mileage oil is a special type designed for vehicles with over 75,000 miles on the odometer. This type of oil is formulated with unique additives and conditioners that can cater to the needs of an aging engine.

High-mileage oil contains seal conditioners that rejuvenate the engine’s seals, preventing leaks. Additionally, it includes detergents that help keep older engines clean, anti-wear additives to reduce engine wear, and friction modifiers to improve fuel economy.

Some high-mileage oils also contain antioxidants to prevent oil breakdown and additional corrosion inhibitors from protecting the engine’s metal parts.

If your vehicle has clocked a lot of miles, high-mileage oil could help prolong its life, maintain performance, and even improve its efficiency. However, not all older vehicles require high-mileage oil.

Standard oil types may still suffice if your car is regularly serviced and in good condition.

How to Choose the Right Engine Oil

Choosing the right engine oil involves considering several factors, including your vehicle’s age, engine condition, operating environment, and the manufacturer’s recommendations.

  1. Vehicle Age and Engine Condition: Newer vehicles with tight tolerances may benefit more from synthetic or synthetic blend oils thanks to their superior lubrication properties and heat resistance. Older or high-mileage vehicles might benefit from high-mileage oil due to its unique additives that cater to the needs of aging engines.
  2. Operating Environment: If you live in an area with extreme temperatures, synthetic oil’s superior performance in hot and cold conditions can benefit you. For moderate climates and normal driving conditions, conventional or synthetic blend oils might be adequate.
  3. Manufacturer’s Recommendations: Always consult your vehicle’s owner’s manual for the recommended oil type and viscosity. Some manufacturers specifically require synthetic oil for their vehicles, particularly high-performance or luxury cars. Deviating from the manufacturer’s recommendations could void your vehicle’s warranty.
  4. Driving Habits: If you often tow heavy loads, frequently drive in stop-and-go traffic, or take many short trips, a synthetic or synthetic blend oil can offer better protection due to its superior resistance to breakdown under severe conditions.

If you’re unsure, seeking advice from a professional mechanic is always wise. They can consider the specific conditions of your vehicle and provide expert recommendations. I can only give you general advice based on my own experience.

Understanding API Ratings

Understanding API Ratings

The American Petroleum Institute (API) establishes and maintains standards for engine oils to ensure that they meet certain levels of performance. You’ll often find an API “donut” symbol on the back of an engine oil container. Understanding this symbol can help you choose the right oil for your vehicle.

The top half of the donut indicates the oil’s performance level. For gasoline engines, you’ll see ratings like ‘SN’ or ‘SM.’ You’ll see ratings like ‘CJ-4’ or ‘CI-4’ for diesel engines. Each letter represents a different set of performance standards that the oil meets, with the latest standard being the highest.

api ratings on motor oil

The center of the donut indicates whether the oil has Energy Conserving qualities. These oils have been tested to provide better fuel economy in comparison to the reference oil.

The bottom half of the donut tells you whether the oil is SAE (Society of Automotive Engineers) certified for viscosity.

The Role of Oil Viscosity

oil viscosity

Viscosity refers to the oil’s resistance to flow or, in simpler terms, its thickness. The correct viscosity is critical for the oil to lubricate your engine properly. If the oil is too thin, it won’t provide enough lubrication. If it’s too thick, it may not flow properly and could reduce your engine’s efficiency.

When choosing engine oil, you will often encounter terms like ‘5W-30′ or ’10W-40’. These denote the oil’s viscosity or its resistance to flow. The first number, followed by ‘W’ (for ‘Winter’), indicates the oil’s viscosity at low temperatures. The lower the number, the thinner the oil, meaning it will flow more easily in cold conditions. The second number represents the oil’s viscosity at 100°C. A higher number means the oil will maintain its thickness and protect the engine at high temperatures.

Modern multi-viscosity oils, such as 5W-30, allow for good engine performance in a wide range of temperatures. Again, your vehicle’s owner’s manual will provide the recommended oil viscosity for your specific vehicle.


Selecting the right engine oil is a critical aspect of vehicle maintenance. It significantly impacts your engine’s longevity, performance, and overall health. Investing time to understand your vehicle’s needs will ensure a long-lasting and high-performing engine.

After all, a well-lubricated engine is a happy engine. And a happy engine leads to a happy driver. Stay informed, choose wisely, and give your vehicle the care it deserves.

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