Can I Use 5W-20 Instead of 5W-30?

Motor oils are rated based on certain factors that include their viscosity, or resistance to flow, and how they handle high and low temperatures. Auto manufacturers suggest a certain kind of oil for each of their various types of engines for a specific reason.

If you’re planning to make a transition, there are some key factors that will help you decide on the better oil for your car.

This article will unfold whether you should switch from 5W-30 to 5W-20.

5W-20 VS 5W-30: Difference and Similarities


The “XW-XX” grading system is used to classify multigrade oils. You can determine the viscosity of your oil by looking at its oil ratings, such as 5W-30 or 5W-20, as in our case.

Simply put, the grade will tell you the flow resistance of the oil at different temperatures. The ‘W’ is used for winter. The number before the “W” denotes the oil’s viscosity (or thickness) at low temperatures (hence winter).

And the number after it denotes viscosity at higher temperatures. For instance, if you look at 5W-20, you’ll see that its viscosity rating contains two numbers, where “W” is for winter and 5 before it, is the winter rating of the oil.

The lower the value of the winter rating, the better the oil for low temperatures.

The second number here, which is 20, represents the viscosity at hot or high temperatures, on the other hand, has a thicker viscosity as its second number, 30, indicates a higher viscosity in hot temperatures.


Climate conditions and the operating temperature of your engine must be taken into consideration before you decide on the best oil for your engine.

Low temperature:

If you want a lower number rating of the oil in colder weather, which means a thin oil that will easily cover the interior of your engine even in the iciest conditions. Cold weather slows down the flow of oil, causing friction.

Both of these oils are winter-grade oils and have the same winter rating of 5. This makes them similar for use in cold weather.

So, if your engine already requires 5W-30, there’s no need to switch. You’re all good.

However, 5W-20 is overall low in viscosity as compared to 5W-30.

High temperature:

You need an oil that can easily hold up to the heat. In this case, the 5W-30 works more efficiently as it has a higher rating as compared to the 5W-20 when it comes to the warmer climate, making it a better option for the summer months. It is thicker than 5W-20 and protects the engine better.

As summer thins out the oil, 5W-30 has a high viscosity that stays lubricating enough and is resistant to heat while protecting the engine parts from wear and tear.

Whereas if you use a low viscosity oil like 5W-20 in the summer heat, it will break down due to heat exposure, causing engine parts to wear out more quickly.


5W-20 is believed to be more economical. In order to save a negligible amount of fuel per car, 5w20 was implemented as an emission requirement by the organization CAFE in the year 2000, with the hope that the combined effect of all cars would have an impact.

Heavy engine oils produce a little bit more drag, which lowers MPG, but never enough for a single car to notice. This comes at the expense of your engine being less lubricated, particularly in hot weather.

How to Pick the Right Oil Type?

You should think about two factors before selecting an oil type:

  • The temperature of your surroundings.
  • The explanation of your car’s engine in the owner’s manual.

Now, this leads to our question:

Can I use 5W-20 instead of 5W-30?

No, it is not advisable to switch to a different oil type for your engine since 5W-30 has a higher viscosity than 5W-20. If your car/manufacturer calls out for 5W-30 oil for your engine, then you should stick to that.

By using oil that your engine wasn’t built for, you run the danger of damaging it. 5w-20 is a fairly light, thin oil that is often made to function with modern engines.

However, you may occasionally substitute 5w-20 for 5w-30 if the manufacturer approves. 5W-30 is thicker and works better in hot climates. If your engine has to face cold weather, then it’s fine to switch to the thinner of the two, 5W-20, for better engine performance during low temperatures.

You can keep on using 5W-30 if your engine calls for it, but if the weather says otherwise. It’s okay to switch.

Also, if you reside in an area where oil changes are necessary due to seasonal changes, you must be willing enough to do so at the cost of the warranty and the long-term performance of your engine.

Then the oil can be changed according to the different conditions.

For the colder winter weather, you can use 5w-20 because it has a lower viscosity and will therefore cause less resistance and friction.

You can switch to 5W-30 in the summer as it lubricates well and guards against wear and tear.

What happens if 5W-20 is accidently mixed with 5W-30?

Nothing too drastic would occur. Combining the two oils often results in decreased engine performance, decreased fuel efficiency, and maybe even engine sludge in the long term.

Although it won’t harm your engine right away, you may eventually start to notice a number of weird symptoms that indicate you’re not using the optimal motor oil for your engine.

Since you accidentally poured 5w-20 instead of 5w-30, it is advisable that you drain the oil and replace it with the proper oil for your engine.

If you leave the 5w20 in your engine, it will attempt to mix with the remaining 5w30 in your oil reservoir.

As a result, none of the oils will provide the maximum level of protection for your automobile’s moving components; this could eventually lead to a significant issue.

Can 5W-20 damage the 5W-30 engine

No, there may not be immediate harm as they share some similar characteristics, such as the same winter rating.

But over time, using an oil other than what the manufacturer recommends will result in poor performance.

The engine would probably perform less efficiently with a different oil viscosity.

The primary (expensive) bearings will be in danger of really rubbing metal to metal if you go from thicker to thinner oil.

As they usually have a substantial oil layer that provides protection against direct contact.

You run the risk of excessive wear, though probably only under extreme conditions, such as when the engine has a lot of miles on it.

Closing thought:

As discussed, 5W-30 and 5W-20 may be used interchangeably in some situations.

You can go ahead and use either oil if you are in a state or nation without extremely high temperatures or if your warranty has already run out.

The 5W-30, however, will be a better option if you live in a warmer environment because of its higher viscosity.

Lastly, you should reach out to your car manufacturer for consultation before you decide to switch oils.