Changing motor oil is one of those small, necessary evils that every car owner has to get used to. If you want to keep your car up and running and in good shape, changing your oil on a regular basis is a must. But the question is, which oil should you get? Can you use 5W-30 oil instead of 5W-20, and if so, why?
To help answer all your questions, I’m going to show you why oil viscosity is so important and how you can find the best motor oil for your car. Without further ado, let’s jump right in.
How Motor Oils Work
Motor, or engine, oil is designed to lubricate the inner parts of internal combustion engines. Also, it helps protect the engine from corrosion and keeps the components cool while your car is running.
Every motor oil is made up of two elements: the base stock and the additives in a 95:5 ratio. While the base stock lubricates the engine and controls the built-up heat, your additives are in charge of controlling oil viscosity and lubricity.
What’s more, all engine oils are rated by their viscosity and grade, and they can be either single-grade or multi-grade. Single-grade oils have a set viscosity level, while multi-grade can act as two different viscosities, depending on the engine temperature.
Over time, all motor oils will start to thicken and get a sludge-like consistency. If you don’t change the oil, it will start looking like jello, and it will lead to poor engine performance.
Not only that but, if you go long enough without an oil change, you could experience complete engine failure. Once that happens, fixing your engine and a blown head gasket costs a small fortune. So to be on the safe side, check and change your oil on a regular basis.
What Is Oil Viscosity?
An oil rating like 5W-30 or 5W-20 will tell you what the viscosity of your oil is. In simple terms, the rating will show you what kind of resistance to flow the oil has at different temperatures.
An oil having a higher rating means that it’s thicker and doesn’t flow as easily as something with a lower rating. That’s why it’s the perfect choice for engines that run hot or if you’re often driving in hot temperatures.
On the other hand, you can put a low-viscosity oil in engines to minimize the flow resistance and keep your car running in cold temperatures.
As I briefly mentioned, multi-grade oils can have two different ratings, depending on the outside temperature. So if you look at 5W-20 oil, for example, you’ll notice that it has two numbers in its viscosity rating. That’s because multi-grade oils have a unique mix of polymers that increase in size when the temperature rises.
When the polymers become bigger, the viscosity of your oil becomes thicker. So the first number you see in the sequence, which is 5 in this case, will show you the winter rating for your oil. That’s the oil viscosity for your motor oil when the temperature is 104°F (40°C).
The second number, which is 20 in this example, shows you how viscous your oil is when it heats up to 212°F (100°C).
5W-30 Vs 5W-20
Since both 5W-30 and 5W-20 have the winter rating, they have the same viscosity in colder temperatures. However, the biggest difference between the two is how they act when the temperature reaches 104°F.
Because 5W-30 has a higher rating, it will become thicker than 5W-20 when the engine reaches its operating temperature. Since a thicker consistency equals an increased resistance, your engine will have a lower horsepower output and fuel economy with 5W-30 oil.
With that said, the 5W-30 offers much better engine protection in warmer climates than the 5W-20. What’s more, it seems to be the more popular choice because you can use it in a wide variety of different vehicles with various engines.
On the other hand, 5W-20 has a thinner viscosity, and it creates less friction than the 30. Therefore, there’ll be less drag throughout the engine parts, including your crankshaft, valve train, and pistons. Also, in colder climates, you can get a better fuel economy with the 5W-20.
Can You Use 5W-30 Instead of 5W-20?
In theory, yes, you can switch from using 5W-20 to the 5W-30 because they have similar viscosity ratings. In fact, often, when you take your car to a mechanic for an oil change, they’ll put the 30 instead of the 20 because it’s thicker.
However, I wouldn’t recommend changing the type of oil you’re using if your car is still under warranty. The moment you put something other than what the manufacturer recommended, your powertrain warranty will become void.
If you’re not sure what the manufacturer’s suggestions are, you can find that information in your owner’s manual. Also, you might find some recommendations for the oil type, and see what other grades are acceptable.
Which Motor Oil to Use?
If you want to go ahead and switch out your oils, I would recommend putting the 5W-30 during the hot summer months. Since it works better in higher temperatures, your car will have a better fuel economy and engine protection. However, if your vehicle has to endure cold weather, consider using 5W-20 since it’s much thinner.
Now, for those of you who don’t experience any extreme temperatures, you can use either type. They’ll both work equally well to protect your engine and ensure that it keeps running smoothly.
Finding the Right Motor Oil for You
Once you’ve settled on the type of oil you want, the tough part will be finding the product that works for you. Before you can do that, you should consider what kind of additives the oil has. Also, you should learn what the different labels and certification logos mean.
Luckily, I’ve written a complete buying guide on motor oils, along with a list of my six favorite products. There, you can read more about when and how to change your oil, and about different types of high-mileage oil.
If you’ve accidentally put the wrong oil in your car, don’t worry, I have the solution for you. Here are my top choices for the best oil extractors currently on the market that will save you a lot of time and money.
As you can see, there are some scenarios where 5W-30 and 5W-20 can be interchangeable. If you live in a state or country that doesn’t have extreme temperatures or if your warranty has expired, I say go for it; put either oil. Both of these oils will protect your car, and you’ll have optimal fuel economy.
But if you live in a warmer climate, the 5W-30 will be a better choice since it has a higher viscosity. Also, if you’re on the fence and don’t know which oil to opt for, I’m sure that my buying guide can help you narrow down the selection.