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Can You Use 5W20 Oil Instead Of 5W30?

There’s so much variety and choice when it comes to shopping for motor oil that it can become quite confusing to know which you can use.

And, just as importantly, which type of oil you should never put into your car.

We have the answer right here if you’re wondering if you can use 5W20 instead of 5W30 in a hurry.

Read on to find out more.

Can I Use 5W20 Instead Of 5W30?

The answer, in short, to the question “can I use 5W20 oil in a 5W30 engine?”, is a resounding no.

pouring motor oil into engine

But why can’t you use 5W20 oil in a 5W30 engine?

It all comes down to how the engine functions.

The viscosity of engine oil proves imperative to how it functions when it is in the vehicle’s engine.

Motor oils serve a dual purpose in a car’s engine:

  • It acts as a lubricant
  • It also keeps the engine cool

The fluid will help your vehicle’s moving parts in working order, free from grinding or sticking together.

But engine oils also serve another important function.

The operating temperature of just about any vehicle’s engine is very hot.

This motor oil will allow the engine to stay cool if it becomes too warm and does any damage to your vehicle.

This is where the oil viscosity rating comes in.

Some engines will require a thicker (i.e., more viscous) to do their job properly, whereas other engines will be hindered from doing their job by a thicker oil.

5w20 oil is thinner and designed for cars with newer engines.

5W30 oil, on the other hand, is a thicker engine oil and is mostly used in older cars, especially those dating before 2002.

So, if your engine requires the extra viscosity that a 5W30 oil will provide, going with a lower viscosity instead could be potentially very bad for your engine, leading to damage.

Below, we’re going to run through what potentially could go wrong if you accidentally (or deliberately) added oil to your engine that’s the wrong weight.

The Potential Dangers Of Adding The Wrong Viscous Oil To Your Car

Here are 4 reasons why you shouldn’t put thinner or thicker oil into your car:


When motor oils are not able to cool the engine correctly, the unwanted heat from using a thicker or thinner oil than needed has the potential to cause damage to the seals and gaskets within the engine system.

When these warp or even crack, you might find that oil begins to leak from your car.

These leaks will require fixing.

Ignoring the fact that you have engine oil leaking from your car will make the problem worse as the cracks become larger over time.

If you do spot oil leaking from your car, or any type of leak, for that matter, you should ensure it’s fixed as soon as possible.

Odd noises

Using the wrong engine oils means that, due to an incorrect oil rating, your engine’s moving parts will not be adequately lubricated.

This will often lead to some grinding.

Grinding will quickly wear your car’s parts down, causing damage that can be expensive to rectify.

If left long enough, it could mean that your engine is damaged beyond repair.

If you do hear any unpleasant or unusual noises coming from your car, get it checked, so the problem can be remedied as quickly as possible.

Lower fuel economy

With fuel prices higher than ever, getting the very best mileage is vital.

While there are other practical ways to ensure good fuel economy, such as not driving overly fast and keeping the right amount of air in your tires, using the wrong type of synthetic motor oil can place all those good practices to the wayside.

If the viscosity of your oil is incorrect, your fuel efficiency will be less as the engine battles more.

When your engine has to do this, it’s forced to use more fuel in order to compensate.

In order to get the very best fuel economy, make sure you use the appropriate oil weight for your vehicle.

Change in exhaust fume’s color

Using a thicker or thinner viscosity will cause the oil to be dirty quicker, which, in turn, creates more carbon that will darken its color.

Alongside any oil leaking from the gaskets, you could begin to see your exhaust fumes turning a different color.

Often, the smoke will turn black and be accompanied by a horrid smelling burnt odor.

Always consult your car’s owner’s manual to make sure you are using the best motor oil for your car.

Additionally, if your car has a warranty, and you put the wrong oil into your vehicle, this could affect it.

Motor Oil Facts

What’s the main purpose of car oil?

Car oil helps to protect critical engine parts, preventing corrosion and chemical damage, as well as cooling the engine.

Oil also helps to ensure the engine is kept clean, as well as conditioning the seals.

How often should I change the oil in my car?

Generally speaking, you should change your oil every 3,000 miles.

A new car, however, will only require its oil to be changed between 5,000 and 7,000 miles.

Final Thoughts

You should never use 5W20 motor oil in a car engine that is only supposed to use 5W30.

If you do, you’re risking doing some serious damage to your engine.

While this won’t transpire overnight, over time, it could lead to some serious implications for your engine.

It’s not worth damaging your car by adding the wrong oil weight.

After all, repairs can be extremely costly, and the inconvenience of not having a car while the problem is looked at can also be troublesome.