If fuel is considered the lifeblood of your car, then motor oil is the red blood cells that keep the engine strong and kicking. But, to improve engine efficiency, you must pick the right type of oil that will regulate temperatures, lubricate moving parts, remove sludge, and clean acids and silicon oxide from the engine. In the automotive world, two of the most commonly used motor oils in modern engines are 5W30 and 5W20. Now, can these oils be interchanged? Can I use 5W30 instead of 5W20?
In general, 5W30 motor oil can be interchanged with 5W20 but under certain conditions. You see, 5W30 oil is naturally viscous than 5W20. This means that this motor oil offers more protection against friction and is resistant to heat, making it hard to break down. As such, this motor oil is a better pick than 5W20 when it comes to engine protection.
But, there are circumstances where interchanging these oils can lead to severe damages to the engine. Since it’s difficult to tell when to interchange them, this short guide will discuss everything you need to know regarding 5W30 and 5W20 motor oils.
Understanding Oil Viscosity
Before we get to our main discussion regarding 5W30 vs. 5W20, let’s just discuss a little bit about oil viscosity. You see, the rate of flow of fluids is measured in viscosity. Hence, viscosity is referred to as the thickness of a fluid and its resistance to flow.
You see, fluids have different viscosities. For instance, water has different viscosity from honey or molasses. Since water flows easily and freely, it’s said to have a low viscosity. On the other hand, molasses doesn’t flow easily making it a highly viscous liquid.
Now, the viscosity rating of motor oil lies between water and honey/molasses. Motor oil is not as thick as molasses nor is it as thin as water. Something else about motor oil is that it comes in different viscosities depending on the type of engine.
For instance, old engines manufactured in the 1990s had much looser tolerances that forced them to use more viscous oils such as 10W30. In contrast, modern engines have seen an improvement in technology that has forced them to employ strict tolerances. What this means is that modern engines can use much thinner oils to lubricate the bearings and all moving parts.
The best thing about less viscous motor oils is that they circulate quicker and freer throughout the engine. Due to their quick circulation, these motor oils provide better lubrication to the engine, which leads to improved engine efficiency hence better performance.
What Do the Numbers Mean?
When comparing 5W30 with 5W20, it’s important that you understand the viscosity numbers and what they mean. Now, any motor oil has a number affixed to its name. This number is considered as a viscosity value as it’s given to oil based on its observed properties. These observed properties are the oil’s resistance to flow when exposed to different temperatures.
Now, motor oils can either be single viscosity or multi-viscosity. Single viscosity oils were hugely used in the past and had one number assigned to them such as 0W, 5W, 10W, 20W, 30, 40, and so on. These oils only protected the engine either during the winter or summer months. For that reason, you had to replace the oil to match the weather demands.
Multigrade or multi-viscosity oils, on the other hand, are newer improvements that feature two numbers in their viscosity ratings. These oils are topped up with a blend of special polymers and additives that increase or shrink the viscosity of the oil to match the outside temperatures. So, when it’s hot, these special additives increase the viscosity of the oil to prevent it from breaking down. When it’s cold, the additives shrink the oil to make it less viscous hence easy to flow.
When it comes to the numbers, you’re likely to see a “W” behind the numbers 0, 5, 10, 15, 20, and so on. This “W” stands for winter. So, any number that’s followed by a W indicates the oil’s viscosity in cold or winter temperatures. On the other hand, any numerical numbers after the “W” refer to the oil’s viscosity in higher temperatures.
In most cases, these numerical numbers are given based on an oil’s ability to travel through an orifice under certain temperatures. So, the longer an oil takes to travel through an orifice, the higher the viscosity, hence the higher the SAE numerical code.
With that said, let’s now compare 5W30 with 5W20 and see whether these oils can be used interchangeably.
5W30 Vs. 5W20
5W30 and 5W20 are two of the most commonly used motor oils in the automotive business. These oils have a lot of similarities and slight differences that set them apart. Both oils share a similar winter rating (5W) that makes them easily interchangeable in cold climates. The main difference, however, comes in when you compare the reaction of these oils under high temperatures.
5W30 for instance has a higher SAE30 rating that makes it more viscous in high temperatures. 5W20, on the other hand, has a SAE20 viscosity rating that makes it less viscous in high temperatures.
Which Motor Oil Should You Use?
So, having said that, can you use 5W30 instead of 5W20 in a car? Is it safe to interchange these two oils? Well, the simple answer is Yes! These two oils can be interchanged. However, there are two factors to consider before interchanging them.
One of them is the manufacturer’s recommendations, where an engine manufacturer strictly states the type of oil to be used in their engines. Remember, failure to follow those recommendations means that you can risk voiding your engine’s warranty.
The second factor is weather conditions. You see, when heated to 212°F or 100°C, the viscosity of any motor oil is likely to change. As for 5W30, the viscosity of this oil tends to be thicker in hotter temperatures allowing it to provide advanced engine protection during summer. As for 5W20, this oil breaks down when exposed to higher temperatures making it quite unlikely to be used in hot temperatures.
With these two factors in mind, it’s easier to argue that 5W20 can be interchanged with 5W30 in high-temperature regions or seasons. However, when it comes to low temperatures, 5W20 is the best alternative thanks to its thinner characteristics. This oil flows with reduced drag allowing it to flow quickly across all engine parts such as the pistons, crankshafts, and valvetrain.
So, can I use 5W30 instead of 5W20? Well, the simple answer is Yes! However, just to stay on the safe side, you must stick to the recommended motor oil grade as speculated by your engine manufacturer. This way, you won’t risk voiding your engine’s warranty.
However, when you consider the viscosity rating, 5W30 is more viscous than 5W20. So if you want to switch oils, 5W30 is a better pick in hot summer months as it doesn’t break down when exposed to high temperatures. This way, this oil will offer advanced engine protection and better fuel economy in hot weather.
On the other hand, 5W20 is a much better pick if you’re using your car in low-temperature regions or reasons. Since it’s less viscous, this oil resists drag when used in cold temperatures, allowing it to flow quickly through all engine parts. This leads to optimal fuel economy and advanced engine performance.
With that said, we believe that this guide has offered value and has helped you narrow down your selection when it comes to 5W30 vs. 5W20.