For a car engine to continuously perform at its peak, it must be oiled (and oil-changed regularly) to keep it from rusting and overheating. Which engine oil should you use, and how does it work?
Let’s take your questions one by one, first things first.
What Is Motor Oil?
Motor oil is a thick fluid used to lubricate the components of an internal combustion engine, and for this reason, it is also called engine lubricant or engine oil.
What does engine oil do?
Engine oil performs three very important roles:
- It lubricates the engine’s moving parts and reduces friction.
- It absorbs heat and prevents engine overheating.
- It coats the engine parts and protects them from wear and corrosion.
Why do cars need engine oil?
An internal combustion engine has many moving parts. As these parts rub against each other, they create friction, which converts kinetic energy to heat.
You may not notice it while speeding off in your car, but several things may be taking place inside your car’s engine:
- Things will heat up – the constant friction will produce heat and may eventually cause engine overheating.
- Efficiency may go down – with kinetic energy converting to heat, more fuel will have to be burned. Thus, there will be an increase in fuel consumption.
- Power output will decrease – lower car performance may result due to reduced power.
- Engine parts will begin to degrade – this may eventually result to engine failure if things go unchecked.
Fortunately, you can do something to prevent this sad fate from happening to your car engine. Start looking for the appropriate motor oil for your car.
What Is Motor Oil Made Up Of?
Engine lubricants are formulated using petroleum-based or hydrocarbon compounds as base oils. They may contain one or more additives or none. Additives enhance the existing lubricating function of the base oil and help address common car engine issues. The most common additives are:
- Corrosion and oxidation inhibitor – prevents rusting
- Dispersant – cleans the engine from sludge and keeps soot particles suspended in oil
- Detergent – gets rid of deposits on hot metal components, neutralises acids, and slows down oil degradation
- Anti-foaming agent – prevents formation of persistent foams
- Anti-wear agent – reduces metal-to-metal contact
- Friction modifier – lowers friction to improve efficiency
- Extreme-pressure additive – decreases wear to parts exposed to high pressures
- Viscosity improver – slows down change in viscosity with variations in temperature
- Pour point depressants – prevents wax crystallisation in oil at low temperatures
- Seal conditioners – restores seals and prevent leaks
What are the different types of motor oil?
There are four major types of motor oil, and each is designed for a specific purpose. Choose the type of motor oil that is suitable to the kind of car that you drive and the extent of driving that you do.
1. Regular motor oil
Regular motor oil is also called conventional motor oil, mineral car lubricant, or standard new-car oil. If your car is a recent model, this type of engine oil will be perfect for it. It is ideal for cars with low mileage (around 2,200 kilometres). A good practice is to never ignore the oil-change indicator when it gives you a warning. If you change your car’s engine oil at 4-month intervals, there will rarely be a need for more aggressive oil formulations.
2. Fully-synthetic motor oil
Cars demanding high levels of performance from the engine require correspondingly high amounts of lubricants. If this sounds like you and your car, you should pick the fully-synthetic type of motor oil. As the name suggests, this oil is chemically engineered. The constituent chemicals are produced under strict laboratory setups to ensure high levels of purity and precision. Under extreme conditions, this type of oil performs better than regular oils.
Fully-synthetic oils have superb viscosity, which means that they tend to be very thick and have exceptional lubricating properties. They offer specialised functions—such as resist oxidisation, modify friction, maintain viscosity under changing temperatures, prevent oil solidification in very cold climates, and reduce motor drag—depending on the kind of additives mixed in with the oil base.
3. Semi-synthetic motor oil
Semi-synthetic, also called synthetic-blend, motor oil is a mixture of synthetic and mineral oils formulated for optimum efficacy of the constituent parts. This type of oil provides the light lubricating properties of regular oil, while also offering some of the specialised qualities of synthetic oils.
Though slightly more expensive than regular oils, synthetic blends are significantly cheaper than fully-synthetic formulas. It strikes the sweet middle ground, so to speak, between regular and synthetic motor oils.
4. High-mileage motor oil
High-mileage engine oils are ideal for cars with over 150,000 kilometres behind them. They are specially formulated with additives that target problems common to older cars and even new cars with high mileage. Older cars typically have issues on leaks and seepage, high fuel consumption, and loss in performance.
This type of engine oil will have higher viscosity and contain higher levels of seal conditioners, swelling agents, viscosity index improvers, and anti-wear agents. Using the correct formulation of high-mileage oils can significantly improve your car’s performance and increase the lifespan of the engine.
What is viscosity in engine oil?
When we talk about motor oils, it’s necessary to talk about viscosity. Here’s an easy way to understand it. Viscosity is simply a description of how easily and quickly oil flows through an engine.
1. Low viscosity motor oil
The oil is thin, and it flows very easily and quickly. If we were to assign numbers, thin oils will be represented by small numbers. Or to put it simply:
Low number = low viscosity = thin oil = quick flow
2. High viscosity motor oil
The oil is thick, and it flows slowly. Following the same logic as above, higher numbers represent thick oils. Thus:
High number = high viscosity = thick oil = slow flow
What do viscosity grade descriptions mean?
You’ve seen motor oils marked with 10W-30, 5W-30, or 0W-20. These are examples of multi-grade motor oil classifications. This method of classifying motor oils takes into consideration the changes of oil viscosity under different temperatures. This is not difficult to understand. You only need to remember the following:
1. Multi-grade viscosity is shown as two numbers separated by a dash. Let’s take an example:
10W-30 has two numbers: 10W and 30
2. The viscosity of multi-grade oil is described in two ways:
- how it flows at engine start-up (low temperature), and
- how it flows at normal operating temperature (high temperature).
Going back to the example given above:
- 10W - the first number represents viscosity at start-up. W stands for winter (or cold)
- 30 - the second number represents viscosity during operation
3. To compare two different grades, take note of their first and second numbers. We’ll take several examples below to illustrate the correct way of making a comparison:
- Comparing 5W-30 and 10W-30: At start-up, the 5W-30 grade motor oil will flow easier than the 10W-30. Both will have the same ease of flow at normal engine operation.
- Comparing a 10W-30 and 10W-40: At normal operating temperature, the 10W-30 motor oil will circulate easier than the 10W-40 grade. Both have the same viscosity at start-up.
What’s the Best Type of Motor Oil for Your Car?
Choosing the best motor oil for your car can be overwhelming with all four types and several grade variations to choose from. The truth is—it’s easier than you think.
You only need to look in the owner’s manual or the manufacturer’s website because it should all be provided there! It will tell you the type of motor oil to use and the recommended viscosity grade and oil-change interval. If, for any reason, you don’t find these details there, it’s best to refer to your mechanic.
Motor oil is a recurring expense added to your car’s operation, but nonetheless necessary. It is vital to your car’s health and performance. So wise up! And never ever think of missing an oil-change schedule again.