Choosing the right engine oil for your car seems like an easy enough job to do, just walk into an auto-shop dealership and buy some oil no? Well it is not as simple as you might have thought.
Car engines are not all the same. They have been built to work with specific oil types, viscosity and an amount of oil in mind. The oil must match the engine’s capabilities, to properly lubricate all the internal parts, keep the engine cool and match the type of driving style.
Engines have become more and more sophisticated with each generation and so did the oil that must be used with them. Some engines can use only full synthetic oils, different viscosity while others can work just fine with almost any type of oil. So choosing the right oil for your car is not just as easy as we think.
In the following lines we will try to explain how to choose the right oil for your car and what to keep in mind when doing so, as using the right oil is the first tool in helping keep your car on the road for a long period of time.
Engine Oil Basics
The challenge in finding the right engine oil for your car comes when you start examining the huge amount of oils available on the market. There are a lot of blends and brands with different additive packages, oils for high and low-mileage cars, different viscosities, long life oils and so on.
To make things even more challenging there are different types of ratings from the European Automobile Manufacturers’ Association (ACEA), the American Petroleum Institute (API), the Society of Automotive Engineers (SAE) as well as your car’s manufacturer standards.
So what all these mean? Let’s break everything down to make things clear.
- API (used in the USA) and ACEA (used in the EU) Rating Symbols: These represent various standards that an oil has been approved for. Your car might require that the oil you are using must have a certain ACEA or API standard so always check your car’s user’s manual to see what are those standards your oil must comply with.
- SAE: SAE refers to oil viscosity and determines how well the oil flows at cold temperatures (-17 degrees Celsius), and at hot operating temperatures (100 degrees Celsius). So the familiar ratings 0W-30, 5W-20, 5W-30, 5W-40, 10W-40 etc. mean the oil viscosity at cold temperatures represented by the first number in front of the “W” and the viscosity of the oil at hot temperatures represented by the number after the dash.
- Type of oil: ACEA, API and viscosity rating are just the beginning. While an oil can be ACEA/API approved and have the required viscosity the oil can be mineral , semi-synthetic, full synthetic or high-mileage. You have to determine what type of oil your car can handle. For example, an old engine with a lot of kilometers can benefit from high-mileage oil, but that is not always the case, as a high-mileage oil might not be compatible with your type of engine and in this case a normal engine oil can be used.
- Additive packages: The oil you put in your engine is not just oil. Oil manufacturers add various chemicals to change how the oil works within the engine. An oil can contain anti-wear agents if different quantities, corrosion inhibitors, seal conditioners to get the most out of an engine.
- Car’s manufacturer standards: this is perhaps the most important thing for you to keep in mind when shopping for engine oil. Not all oils are compatible with all types of engines and car brands so you must consult your car user’s manual to see what you should look for on the bottle to make sure the oil is compatible with your engine. Each car manufacturer has it’s own oil standard approval code so make sure you look for that code before going further.
Which Engine Oil Is Right For Your Car?
Most car manufacturers will often suggest two or more motor oil viscosities for your engine, such as 5W-30 and 5W-40 for example, based on different factors such as operating conditions, operating temperatures, driving conditions and so on. So why is viscosity so important?
Viscosity represents the oil’s resistance to flow and it is represented with the common “XW-XX”. The “W” stands for winter and the lower the number in front of this “W”, the less an oil thickens during cold temperatures. The second number after the “W” indicates the viscosity of the oil measured at 100 degrees Celsius. This number represents the oil’s resistance to shattering and thinning at high temperatures.
Now with viscosity out of the way, now we can have a look at what oil type to buy. Most of us follow the 12-month, 10000 Km oil change rule. Frequent oil changes means less tendency to need other types of oil than conventional so no need to look for more expensive oils unless so desired. The car’s user’s manual as well as the following lists will provide you with a good idea of what type of oil to choose according to your needs.
- Conventional oil (Mineral oil): This type of oil is the most common and is the cheapest oil you can buy. Most will have the proper SAE, API and ACEA standards but they do not offer a lot of additives. These kind of oils are perfect for persons that do oil changes frequently and have well maintained engines
- Full-synthetic Oil: These are the oils made for newer and high-tech engines. These oils are superior long-lasting performance in all critical areas, from protection against carbon deposits inside the engine to viscosity index. They flow better at low temperatures, have better resistance at high temperatures and contain a lot of additives for better engine protection. While it sounds like the ideal oil type for any engine, all this comes at a cost. Full-synthetic oils may sometime be 3 to 4 times more expensive than a conventional oil.
- Semi-synthetic or Synthetic-blend oil: This is basically conventional oil but with a dose of synthetic base. They are built to offer improved protection during heavy engine use. They are lower priced than the full-synthetic oils and offer decent protection and sometimes similar to full-synthetic oils
What Are The Additives in Motor Oil?
Now that we have seen the main types of oils you have to take into account the additive packages that an engine oil has as they are an important factor to take into account. Here are the most common found additives used for an engine oil:
- Anti-wear additives: used to prevent the loss of lubrication when the film created by the oil breaks down
- Detergents: used to remove carbon deposits, rust and corrosion
- Foam inhibitors: used to remove the foam created by the crankshaft rotating through the oil as a foamy oil does not provide proper lubrication.
- Friction modifiers: used to reduce engine friction and improve the life of the oil
- Viscosity improvers: used to improve the oils resistance at high operating temperatures.
While a motor oil heavy on additives is a good thing, these additives must be properly balanced as they can do more harm than good. Sulfur compounds provide anti-wear properties but they can and will reduce fuel economy and affect your catalytic convertor. Also too much detergent can damage the anti-wear balance of the oil, while friction-reducing additives can affect the life of the catalytic convertor.
How the additives work is very dependent on the base oil (synthetic or mineral), viscosity, type of oil and a heap of other things. Every oil manufacturer has its own recipe and some will do well with your engine, while others won’t.
How Do I Know What Engine Oil to Use?
One of the best ways to find the proper oil for your car is to use the car’s manufacturer’s recommendations and work your way from there. Always do a little research on discussion forums for the car brand you are driving and see what others are using. There is no proper way to know for sure what oil will be the best oil for your car, but by seeing what others are using you can make an educated and informed decision for your next oil change.
Also keep in mind that changing your oil frequently, as well as replacing the oil filter with each oil change, play an important role in keeping your engine in proper operating conditions for a long period of time.
Here is a short but comprehensive video on how to choose the right engine oil for your car made by TOTAL one of the biggest oil manufacturers: