We often confuse motor oil grades and use the wrong oil, which impacts the engine’s performance and durability. To choose the right oil, you need to understand different oil grades and how they perform in different conditions. Take 0w40 vs 5w30, for example.
Both 0w40 and 5w30 are synthetic multigrade oils. 0w40 has a lower viscosity at low temperatures and a higher viscosity at high temperatures. This makes 0w40 a more all-round engine oil. But 5w30 is more suitable for warmer temperatures.
You will learn their similarities and differences in detail. Besides, you can also determine which oil to use for your car and when.
0w40 vs 5w30: Quick Comparison
The following chart will show you the differences in the properties of these oils.
| Properties | 0w40 | 5w30 |
| Viscosity Index | 180 | 159 |
| Low-Temperature Viscosity | Low | Higher than 0w40 |
| High-Temperature Viscosity | High | Lower than 0w40 |
| Low-Temperature Range | -40°C or -40°F | -35°C or -31°F |
| High-Temperature Range | 40°C or 104°F | 35°C or 95°F |
| Oil Consumption | High | Low |
| Fuel Consumption | Low | High |
Understanding 0w40 vs 5w30
0w40 and 5w30 are grades of synthetic motor oils. These are multigrade oils, which means the same oil behaves like oils of multiple grades. The viscosity of these oils changes according to temperature changes. This is why they are called multigrade oils.
The number on the left denotes the viscosity level of the oil at low temperatures. For example, the 0 in 0w40 indicates that this oil has a low viscosity when cold. Viscosity is the measurement of how thick or thin a fluid is.
You might understand viscosity better with a real-life example. If you pour three fluids, water, oil, and honey, on a sloped surface, which one will go down first? Of course, water because it has a very low viscosity. So, its flow rate is higher.
Oil will have a medium viscosity, while honey will have the highest. So, the honey will be much slower than other fluids. Depending on how slow or fast a fluid flows, it is given a viscosity rating.
The viscosity rating of 0w40 at low temperatures is very low. So, this stays thinner when it is cold outside. As the temperature rises, its viscosity will also rise. At the highest working temperature, it will be thicker to prevent breakdown. On the other hand, 5w30 has a higher viscosity than 0w40 at low temperatures. When the temperature rises, its viscosity will also increase, but not as much as 0w40.
0w40 vs 5w30: What Are the Differences?
You might have already guessed how these oils are different. Still, let me clarify the differences further.
Viscosity Index
0w40 has a higher viscosity index, which means the oil has a more stable lubricating performance throughout the temperature range. So, it will be suitable for a wide range of temperatures. But 5w30 has a lower working range because its viscosity index is low.
Low-Temperature Flow
Say you are living in a cold climate region, and the temperature outside often drops way below the freezing point. For example, the outside temperature may be -40°C or -40°F. If you use 0w40 in this situation, it will flow easily through the engine.
So, the engine components will be well-lubricated. It is helpful for cold starts. But if you use 5w30, it will flow slower than 0w40 because 5w30 has a higher viscosity at low temperatures.
High-Temperature Flow
The situation turns upside down at high temperatures. After you have driven your vehicle for some time, the engine will be at its normal operating temperature. At that point, 0w40 will be thicker. It will ensure the oil doesn’t break down easily to produce sludge and keep the engine lubricated.
But, as 5w30 has a lower viscosity at high temperatures, it has a higher possibility of breaking down. The oil will be thinner and can withstand less loads than 0w40.
Engine Performance and Durability
It may sound confusing, but lower-viscosity oils aren’t great for engine performance in the long run. These oils break down faster, resulting in sludge or deposits in the engine. As a result, the engine loses its efficiency and service life.
0w40 is only good for the engine if you regularly drive the car in low-temperature regions. In that case, the oil will be thinner at low temperatures, which is beneficial. Its thickness will increase with the temperature, lowering the risk of breakdown.
When you are driving in warm weather, 5w30 oil is good for startups. But as the engine becomes hotter, the oil will be thinner. So, you run the risk of drying out engine components.
Oil Consumption
These oil grades have almost similar oil consumption. When 0w40 is thin at low temperatures, it has a higher consumption rate. But as it gets thicker, the consumption rate drops.
For 5w30, this gets the opposite. This oil has a lower consumption rate when cold. But, as its viscosity drops at high temperatures, its consumption rate increases. As 0w40 is thinner at low temperatures, it will have a slightly higher consumption rate.
Fuel Efficiency
You can guess this from the previous property. When the oil consumption is easier due to low viscosity, the engine consumes less fuel. The engine components get lubricated faster, so the engine can work more efficiently.
But 5w30 is thicker in the beginning. So, engine components take time to get properly lubricated. It reduces the engine efficiency at first, which causes the engine to consume more fuel.
Price
Both of these oil grades are priced similarly at $27.97. Depending on the brand, you might see a slight variation in their prices. But that difference is negligible.
Both oils will provide a similar service life, so the cost-to-value proportion is almost the same for both oil grades.
0w40 vs 5w30: Which One Should You Use?
There is no definite answer to this question. You should choose engine oil based on your engine, manufacturer’s recommendation, place of use, etc.
0w40 is a better oil for cold climates because it flows better when the temperature is low. 5w30 will not be highly suitable for cold starts. But if you are in a warm climate region, both oils may be suitable for you. Especially 0w40 performs better at high temperatures. On top of that, you should follow the manufacturer’s recommendation to keep the engine safe for a longer period.
FAQs
The following answers to some commonly asked questions about these oil grades might help you.
Q: Can I use 5w30 instead of 0w40?
If you don’t live in an extremely cold area, you can replace 0w40 with 5w30. But it might cause your engine to wear faster.
Q: Do 0w40 and 5w30 last the same?
The lifespan of these synthetic oils is almost similar. Both of these oils will last for about 10,000 miles under standard driving conditions.
Different oil grades are better in different situations. So, there is no definitive way to declare one better than the other.
Final Thoughts
Choosing the right engine oil greatly impacts the engine’s performance, fuel economy, and engine’s durability. To get the maximum performance from the engine and keep it running for a long time, you should only use the engine oil suggested by the manufacturer.
If you ask which is better, in 0w40 vs 5w30, I will recommend considering the above factors. Think about your driving conditions to figure out which engine oil you need. 0w40 is better for colder areas, and 5w30 is a good overall oil for warm areas.