The Best Engine Flush Products

Table of Contents

There’s nothing quite like a good flushing out of your system. It doesn’t matter if it’s your semi-clogged shower drain, your own body, or your engine; putting any system through a thorough internal cleanse will leave you running more cleanly and more smoothly. Your engine internals are no different to your arteries or your sinuses: they can become clogged and contaminated with sludge and gunk. Sometimes, a thorough reset can rejuvenate your motor. A caveat: even the best engine flush products do little for new, low-mileage cars that are well maintained and driven properly. However, if you’ve got an older car, especially one you only drive on short trips or one whose previous owners weren’t as consistent with oil changes as they should be — an engine flush can help your car run better.

The reason engine flush products exist is because your oil becomes contaminated over time. Some of that contamination is environmental and can be caused by dirt and grime that makes its way into your internals. Some of it is just a natural function of the chemical reactions and stress that happens inside hot engines. Some is because of temperature fluctuations and moisture buildup. This last one is especially true if you only drive short distances. In that instance, your lubricants never get up to temperature and so the moisture doesn’t evaporate. Moisture is public enemy number one for all cars.

As a result of all these different contaminants, your galleys can become clogged with sludge and there are all sorts of deposits and residues left throughout your engine. That makes even freshly changed oil less effective at protecting your motor, and causes more drag, more wear, and more damage to your car. Build up from bad or burnt oil can cause your piston rings, valves, and other components to become sticky and prevent them operating effectively. Engine flushes can help with this and even help soothe valve noise; by removing the sludge from under your rocker covers, it can improve the lubrication for your valve lifters. Check out our list below of the best engine flush products to buy for your cars and trucks.

1. Editor’s Pick: Atomex Total Flush

1. Editor’s Pick: Atomex Total Flush
  • Easy to use
  • Effective
  • Price

This engine oil treatment is a hard-core weapon against carbon build up and gummed-up components.

This Atomex Total Flush promises to clean the crankcase ventilation system of your car while also stripping away gunk from your valve chain. That gunk can prevent the valve guides from functioning correctly and this product frees those parts up. It also cleans the grime from piston rings, enabling them to float the way they were designed and reducing friction within your cylinder head. Where Atomex differs from all the other offerings on our list is that it allows you to drive with the product in. In fact, they recommend your drive for 150 to 200 km before performing your oil change for a deeper cleanse. The benefit of that is you can use this product, and then have your dealer perform your change for you. This is also a smaller dose, only 250mL is needed to treat up to 5L of oil, which means you won’t risk overfilling your motor when using it. This is more expensive than others on this list, but when you consider the convenience and potency of this product, it’s worth paying a few bucks more.

2. Runner Up: Liqui Moly 2037 Pro-Line Engine Flush

2. Runner Up: Liqui Moly 2037 Pro-Line Engine Flush
  • Effective
  • Reliable
  • Coverage

This engine flush is a potent addition to the company’s line-up of premium lubricants.

This Liqui Moly 2037 Pro-Line Engine Flush consistently removing corrosion, deposits, and contaminants from your engine. Those little nasties are lifted from the surfaces of your motor and dissolved into your fluid when you change it which you should do immediately after use. Drivers report less valve noise, less sludge, and a generally happier motor after applying this treatment. This product is safe for diesel, gasoline four-stroke engines,and turbocharged engines as well as seals and gaskets so it won’t damage your car if used correctly. One 500mL bottle is recommended for engines that take 5L of oil, so if you have a larger displacement motor you might need to buy more than one can.

3. Best All-Purpose: Red Line (60103) Complete SI-1 Fuel System Cleaner

This all-purpose detergent based fuel additive works to clean all forms of fuel injectors, carburetors, valves, and combustion chambers by using a concentrated blend of some of the most powerful high-temp and low-temp detergents on the market.

To see the best results, use one bottle of this Red Line (60103) Complete SI-1 Fuel System Cleaner per tank and watch as it effectively cleans out varnish and gum. Aside from enhancing fuel stability, this cleaner will reduce your need for octane by up to two points. Not to mention, this system cleaner can be used with oxygenated fuel and can be used continually.

4. Best Dual Purpose: Amsoil Engine and Transmission Flush

4. Best Dual Purpose: Amsoil Engine and Transmission Flush
  • Effective for engines and transmissions
  • Expensive
  • Hard to use on transmissions

This dual-purpose solution provides drivers with a cleaning and degunking product for both engines and transmissions.

The heavy detergents in this Amsoil Engine and Transmission Flush lift and dissolve contaminants, helping clear oil pathways and passages. In motors, this product reduces buildup that causes sticky piston rings and valvetrains. In automatic transmissions, it cleans out the filter and the oil galleys to promote more effective cooling and lubrication. It's easy to use on engines but Amsoil recommends you do not use it on automatic transmissions that don’t have a removable oil pan or filter. If you do have the right type of transmission and the know-how, this product is an affordable way to give your gearbox a new lease on life. This is the most expensive additive solution on this page, and the most expensive by volume, but users report excellent and photo-verified results especially underneath the valve covers where sludge settles most.

5. Most Versatile: Sea Foam SF-16 Motor Treatment

This product lubricates upper cylinders to ensure your vehicles run smoothly for longer periods of time. In fact, this motor treatment can stabilize diesel and gas fuels for up to two years.

Suitable for both two-stroke and four-stroke gas and diesel engines, fuels, and oils, this safe and easy-to-use Sea Foam SF-16 Motor Treatment provides your vehicle with a blend of cleaning and lubricating ingredients that liquify built-up gum residues and varnish deposits from fuel passageways, intake valves, pistons and chamber areas.

6. Best For Salt Water: CRC SX-32 Salt Terminator Engine Flush Concentrate

This engine flush concentrate was specifically created for any type of engine that comes in contact with salt water.

When talking about engines, motor vehicles like cars and trucks are most likely the first types of machinery that come to mind. But cars aren’t the only machines that require a good flushing every once in a while; motorcycles, trailers, boats, and diving gear will also need a tune up. Simply spray this CRC SX-32 Salt Terminator Engine Flush Concentrate onto any surface that’s been exposed to salt water or attach it to your engine's flushing unit to protect your belongings from corrosion while extending it’s life.

How to Use an Engine Flush

Most engine flushes are used the same way, but there may be slight variations in the theme from one product to another. The most critical thing you can remember is to always read the instructions. These products can do harm to your car or truck if used incorrectly. And, while they’re inexpensive, if you don’t use them correctly you’re just wasting your money.

The general steps are the same:

1. Drive for a few minutes to warm the engine.

2. Add the specified amount to your oil while your motor is still warm.

3. Run your engine at idle speed — usually for 10 minutes.

4. Perform an oil and filter change immediately.

5. Job done.

It is important to do this while you’re car is warm because that’s when oil is at its best performance level. It’s also easier for the detergents in the flush product to do their job at temperature. Idle, don’t drive, because the additive isn’t as protective as regular oil. You can damage your engine if you stress it while the detergents are working. Change your oil immediately so that the sludge and grime doesn’t have a chance to resettle.

What if My Motor is Really Bad?

If your motor is already caked in this sludge, these detergents might not be enough to solve the problem. The good news is — they are inexpensive. It might be worth trying two, or even three, flushes and changes in fairly quick succession, less than a 1,000 km between each one, to see if that will make an impact.

Will an Engine Flush Stop a Car Blowing Smoke?

No. By the time a car is blowing smoke it is burning oil. That means lubricant has found its way into the combustion chamber. An engine flush can’t repair the metal components that form these seals. In some cases, a head-gasket repair solution or engine repair additive may work. But a flush can only help clean your oil galleys and valve train, nothing more.

How Do I Know If I Need an Engine Flush?

If you regularly perform your oil changes, you might notice that your oil is coming out more black, thick, or even chunky than it ever has in the past. Your oil should be a brown-honey colour, even at the end of its lifespan. If your oil is particularly dirty or thick, it might be because of heavy contaminants in your motor. You’ll also know if you’ve started using more fuel. That’s because the sludge that clogs your oil systems can prevent oil lubricating the cylinder walls properly. It can also clog your valve train, including the cam shaft and timing chain, which can add drag to your engine.

Safety Tips for Engine Flushes

Remember, an engine flush is a heavy-duty cleaning chemical that is harsh in nature. You should always wear protective equipment, including heavy-duty gloves when handling this product. It can and will cause irritation to skin. You should also wear protective glasses and avoid touching your eyes. Lastly, be mindful that your engine bay is hot and can cause burns.

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