Engine oil is required to keep your engine running smoothly and to protect it from damage. However, it collects dirt and requires regular replacement. In this blog post, you’ll learn five important things about oil so you’re better informed when you get your next oil change. 

How Oil Gets Dirty in the First Place 

Dirt and debris accumulate in your engine through the following situations: 

• poor-quality engine oil and oil filter 
• poor-quality air filter 
• frequently driving on dusty roads 
• poor maintenance 
• driving hard 
• mostly short drives, i.e., under 20 minutes 

Your engine isn’t a closed system, and oil helps lubricate, cool, cushion, and seal it. Low-quality engine oils inadequately lubricate the engine’s components, resulting in increased friction and therefore metal shavings. A low-quality filter exacerbates the problem by allowing debris to circulate back through the engine. 

Depending on your vehicle, driving habits, and the season, your automotive technician may recommend different oils. 

Types of Engine Oil: Synthetic vs. Conventional 

Engine oil comes in four main types: conventional, synthetic, synthetic blend, and high-mileage. An oil’s job is to protect your engine, so let’s compare them on that function. 

Synthetic engine oils have trace amounts of the original petroleum product left in them. They have a naturally higher viscosity than conventional oils. This means they handle extreme temperatures better and can stand up to intense driving conditions, such as towing. 

Conventional oil is mostly a petroleum-based oil. It is usually the thinnest of the four types and works best in vehicles manufactured before 1990. It costs less and can improve engine efficiency and reduce emissions. 

Synthetic blend or semi-synthetic oils are a mixture of both. High-mileage oil contains additives to help protect engines with over 100,000 km on them. 

Your automotive technician will recommend not only which type of engine works best with your vehicle, but also which viscosity rating best suits the upcoming seasons. 

Oil Viscosity 

Oils are rated according to their ability to protect your engine in the cold. 

These ratings essentially measure how thick engine oil remains in a range of temperatures and are called viscosity ratings. Common viscosity ratings are 0W-20, 5W-20, or 5W-30. 

But how do you read that? 

• The first number refers to the oil flow in cold weather. 

• “W” stands for winter. 

• The second number refers to the oil flow at 100°C. 

The lower each the number, the less viscous the oil and the quicker it will flow. 

But don’t assume that lower is better in the winter: a lot depends on your engine’s construction. 

Synthetic oils work best in the cold because they have a lower pour point (the lowest temperature at which the oil flows). 

You can also consider multi-grade oils, which can be used year-round (depending on average temperatures in your location). These oils are made with chemicals known as viscosity index improvers, which allow the oil to run thinner in the cold and thicker in the heat. 

Does Engine Oil Have a Best-Before Date? 

Actually, yes. Unopened conventional engine oil lasts about five years. Most synthetic, synthetic blend, and high-mileage oils last seven to eight years when sealed. Once opened, all engine oils last about a year. 

This affects, in part, the frequency of oil changes. 

How Often Should I Have My Engine Oil Changed? 

Over time, your engine oil will become less viscous and less efficiently lubricate the moving components of your engine. 

The general guideline for most vehicles is to change the oil at least every six months or every 5,000 km to 12,000 km. You’ll likely reach 12,000 km or even more with synthetic oil. 

However, if you regularly drive less than 20 minutes at a time, the engine won’t get hot enough to burn off moisture. This can lead to corrosion, potentially harming your engine. This means that, even if you don’t reach the minimum threshold of 5,000 km before your next oil change, have it done anyway. 

Which Oil Is Best for My Engine? 

Synthetic oils are ideal for most modern cars and diesel engines. However, using synthetic oil in an older car, especially one with high mileage, can cause leaks that force the engine to burn more oil and require more frequent replenishment. 

Some older models and many performance cars need an oil switch when the weather gets hotter. Your car could need 0W20 or 5W20 in the winter but might require 5W40 or even 10W60 in the summer. 

Your automotive technician at your local NAPA AUTOPRO shop will recommend the right oil for your vehicle.