Home / Articles / Car Guide / Engine Flushing: What is It and Why You Need It

Engine Flushing: What is It and Why You Need It

Team AckodriveSept 21, 2023

A car’s engine is the vital component that keeps the vehicle “alive” or, say, in motion. Regular oil change and engine maintenance is something which you shouldn’t ignore. However, engine maintenance is more than just an oil change. Engine flushing is a crucial process that comes in handy in circumstances like irregular engine oil changes, prolonged non-usage of the car or any other engine-related issues. Read ahead as we explain the process of engine flushing in detail.

What is Engine Flushing?

Engine flushing refers to a process of cleaning or flushing out the sludge or carbon build-up inside the engine. The process involves using engine flush additives to remove the impurities. Engine flushing removes carbon deposits and other impurities built upon the engine's internal components.

The carbon deposits or sludge formation can be due to several factors such as ageing of the engine, use of low-quality fuel/engine oil, improper fuel composition or irregular oil change. The sludge formation inside the engine can lead to a drop in power output and other complications, which we will explain in the following sections.

How is Engine Flushing Done

Engine flushing is a simple process which requires a high-grade engine flush additive to remove the sludge and carbon deposits inside the engine.

There are three methods of engine flushing. Your mechanic will determine the best method depending on your car's engine condition.

Method 1: Take Your Car Out For a Short Drive

Drain out a small amount of oil from the engine.
Add the engine flush additive through the oil filler port.
Next, you take the car for a short spin so that the chemical can reach the nook and corner of the engine.
The chemical composition removes the sludge and carbon deposits. The impurities get settled in the oil and oil filter.
Finally, the mechanic changes the oil filter and engine oil.

Method 2: Engine Idling

Drain out a small quantity of engine oil and pour the additive via the engine oil filler port.
Start the engine and let it idle for around 5 to 10 minutes. Note that this method does not require you to take the car for a short drive.
The engine flush additive circulates throughout the engine and loosens up the sludge.
The impurities get deposited in the oil filter or settle on the oil sump.
Lastly, the mechanic changes the engine oil and replaces the oil filter.

Method 3: Drain Out the Oil and Flush

Drain the engine oil as you would do during an oil change.
Pour clean engine oil and the flush additive into the oil filler port.
Start the engine and let it idle for a few minutes. The chemical mixed with the oil circulates to every corner of the engine.
The additive clears the sludge/carbon deposits, and it gets settled in the oil filter or oil sump.
Finally, the mechanic can change the oil and the fuel filter.

Benefits of Engine Flushing

Here are the advantages of engine flushing

Engine flushing prevents and removes sludge formation. It saves you from hefty repair bills by avoiding the harmful effects of sludge on the internal engine components.
Flushing also removes carbon deposits that form over some time.
If the vehicle is parked for an extended period or you don't drive the car as much, the engine is unused. It's a perfect condition for sludge formation. Performing an engine flush in such a scenario can improve the engine's longevity.
If you are purchasing a used car and do not have any documents related to engine maintenance, an engine flush can save you from costly repairs.
An engine flush cleans the internal of the engine, and in turn, it results in the efficient functioning of the engine. An efficient engine returns good fuel economy.

Engine Flushing: Why Do You Need It?

The answer to this question depends on various factors such as the vehicle’s age, maintenance history and engine performance. The following points explain the different scenarios where your car may need engine flushing.

If the vehicle is old or has covered more than 40,000 km, then your car needs engine flushing. With more and more kilometres, the engine's internals are prone to carbon deposits and sludge formation. Hence, the flushing process keeps the engine healthy, and you will not experience any performance drop.
If the car is not maintained correctly or the engine oil is not changed as per the manufacturer's recommendation, the chances of sludge build-up are high. Flushing the engine can clean the internals of the engine.
If you continuously drive your car in stop-and-go traffic or drive only a few kilometres per month, then you should consider engine flushing every 30,000 to 35,000 km. That's because driving under such conditions causes the engine oil to leave deposits, and flushing the engine cleans the sludge build-up.
Your car requires engine flushing if it's parked for a very long time. The engine oil can build up sludge, and it can damage the engine's internals. Hence, it's advisable to clean the internals before driving the car.

How Does Engine Sludge and Deposit Form?

The following points explain how sludge and deposits form inside an engine.

Engine oil circulates throughout the engine and lubricates all the moving components. In other words, engine oil should be in motion inside the engine.
When you don’t drive the car for a very long time, drive in stop-and-go traffic or drive very short distances for a very long time, the engine oil starts leaving deposits on the internal components.
Apart from sludge, carbon deposits also build up over time. They are nothing but the by-product of improper fuel combustion. Similar to sludge, it gets collected on the internals of the engine. It can lead to a performance drop.
The deposits keep building up and form sludge. The sludge can hamper the oil flow inside the engine.
If ignored, it can lead to severe problems like malfunctioning spark plugs, valves and essential sensors. You may also find soot coming out of the exhaust if there is too much sludge formation inside the engine.
In the worst-case scenario, you may need to replace the engine if it gets seized due to the lack of lubrication.

Engine Oil Sludge Formation: How to Determine

So, how do you determine the formation of sludge inside your car’s engine? It does not require extensive knowledge about the functioning of an engine. All you have to do is keep an eye on some of the symptoms that point towards engine sludge. Below are the symptoms of an engine with excessive sludge formation.

Check engine light: Your car’s check engine light may light up if there’s an issue with the engine components. The sludge/improper oil flow can damage the components and sensors. Hence, the engine check light will warn you about the malfunction. It would be best to immediately visit the service centre when this light comes on.
Check oil light: A check oil light turns on when there’s insufficient oil or low oil pressure. The latter is caused due to sludge inside the engine. The thickened engine oil can also trigger the check engine oil light. Whatever might be the reason, you should immediately get the engine checked when you see this light on your car’s dashboard.
Low fuel efficiency: The engine is stressed and has to work harder due to the thick and sticky sludge deposited on the engine components. It results in increased fuel consumption. In turn, it will reduce the fuel economy. If the mileage drops without you changing your driving style, it indicates sludge formation.
Engine overheating: As mentioned earlier, the role of engine oil is to lubricate the moving internal components and reduce friction. The sludge does the exact opposite. It increases friction between the moving engine components. The friction causes heat, leading to an engine overheating problem. If your car overheats, it may be due to sludge formation.
Also, read: How to check engine oil level in a car?

Frequently asked questions

Here are some of the most commonly asked questions about car engine flushing.

Why do I need to flush my car’s engine?

Engine flushing is done to flush out the impurities in the form of sludge and deposits inside the engine. The process is done by using engine oil additives to break down the sludge formation or carbon deposits.

Is it good to flush my car’s engine?

Engine flush will not cause any harm to your car’s engine. It cleans the internal engine components and improves the performance, mileage and engine life. Hence, it’s good to flush your car’s engine. However, you may not require an engine flush unless you notice sludge or carbon deposit symptoms.

Will the engine flush cause damage to the engine?

No. An engine flush will not cause any damage to the engine. In contrast, it keeps the engine clean by removing sludge and carbon deposits.

What happens if I leave the engine flush in for too long?

Engine flush liquid is a chemical, and you should not leave it inside the engine for too long. The chemical additives can damage the engine components. Hence, it would be best to use it only before an engine oil change.

Will the engine flush improve fuel efficiency?

Yes, engine flush can improve fuel economy, provided the mileage has dropped due to carbon particles or sludge formation. However, an engine flush cannot dramatically increase fuel efficiency.

Is it good to flush my car’s engine?

Will the engine flush cause damage to the engine?

No. An engine flush will not cause any damage to the engine. In contrast, it keeps the engine clean by removing sludge and carbon deposits.

What happens if I leave the engine flush in for too long?

Will the engine flush improve fuel efficiency?

Yes, engine flush can improve fuel economy, provided the mileage has dropped due to carbon particles or sludge formation. However, an engine flush cannot dramatically increase fuel efficiency.

Explore More:

Topics

Car FAQs

Electric Vehicle Guide

Home / Articles / Car Guide / Engine Flushing: What is It and Why You Need It