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What’s an Engine Flush, and Does Your Car Need One?

Suppose your car is old and has not been checked for a long time. Now the engine overheats or sometimes takes too long to start. When it’s running, you hear strange clicking or knocking sounds.

When a vehicle has been neglected for too long and goes without routine maintenance, such as regular oil changes, the oil that lubricates the engine can get contaminated with foreign substances and form sludge. Sludge filled engine can lead to problems like contaminating the injected fuel or preventing the spark plug from igniting.

In a case like this, you might consider an engine flush. Here we’ll discuss what an engine flush is, why it’s done, and how to know if your car needs one.


What’s an Engine Flush?

To clean the inside of an engine and remove any debris that may have built up there, you can use flushing oil. This process is called an engine flush. There are different ways of flushing an engine and we will let you know two representative methods.


Use Flushing Oil and Allow Car To Idle

An image showing how to do engine flush making an engine idling
You can add flushing oil and idle the car to remove the sludge.

Usually, you can drain the oil from your engine, add flushing oil and idle the car to remove the sludge before adding new oil. This is the least expensive method of flushing an engine, and it doesn’t take very long.


Use Suction Machine With Flushing Oil

An image showing how to do engine flush with a suction machine
You can use a suction machine with Flushing oil to suck out the sludge.

If your engine is extremely sludgy, you might consider using a suction machine to suck out the engine oil along with all the oil residue. This method is more complicated, but the suction machine is equipped with a fine filter that can remove oil debris more thoroughly. Most car repair shops have suction machines, just in case you want to use this method to flush your car’s engine.


Does My Car Really Need an Engine Flush?  

A poster illustrates a debate over whether to perform an engine flush.
Does Your Car Need an Engine Flush?


Yes, If It’s Clogged With Sludge

If an engine’s circulation system is clogged with sludge and debris, lubrication is less effective and this can cause friction within the engine. Over time, significant engine damage can result, and removing the debris can improve engine performance.


Most of the Time, Probably Not

With proper servicing and regular oil changes, your car will probably never need an engine flush. Newer car engines have been developed with durability and minimal maintenance in mind, and their manufacturers warn against flushing because it can sometimes cause damage.


There are different opinions on when an engine flush is necessary, if ever. The consensus, though, is that it should not be undertaken frequently. Engine oil is needed to lubricate an engine’s components, and cleaning the engine too often can interfere with lubrication.

Another thing most experts agree on is that you should consult a car service professional when deciding if your car needs an engine flush.


What Can I Expect After an Engine Flush? 

After an engine flush, your car’s performance should improve and the engine may last longer. You may be able to delay an engine replacement or other costly repairs. Other benefits include better fuel economy, enabling you to save money on gasoline, and better lubrication, reducing wear and tear on parts. Without the sludge buildup in your oil system, the new engine oil will be cleaner, reducing the need for frequent oil changes.

If you decide your car needs an engine flush, read our next article to learn exactly how it’s done and what precautions to take.