What Is The Best Engine Flush? (2020 Reviews)

Best Engine Flush - Reviews

If you’re looking to get more life out of your engine, an engine flush is an easy, no-frills option that can positively impact your vehicle’s performance. The best engine flush offers superior cleaning without causing further damage and isn’t much more complicated than a standard oil change.

Quick Picks: Compare 2020’s Best Engine Flush Brands

Our #1 Pick
Liqui Moly 2037 Pro-Line Engine Flush
Runner Up
Golden Touch 1698 Fast Flush Engine Flush - 128 fl. oz.
Also Consider
High Milage Engine Flush Formula, Oil Cleaner for Cars and Truck, 15 Oz, STP
Liqui Moly 2037 Pro-Line Engine Flush
Golden Touch 1698 Fast Flush Engine Flush - 128 fl. oz.
High Milage Engine Flush Formula, Oil Cleaner for Cars and Truck, 15 Oz, STP
Our #1 Pick
Liqui Moly 2037 Pro-Line Engine Flush
Liqui Moly 2037 Pro-Line Engine Flush
Runner Up
Golden Touch 1698 Fast Flush Engine Flush - 128 fl. oz.
Golden Touch 1698 Fast Flush Engine Flush - 128 fl. oz.
Also Consider
High Milage Engine Flush Formula, Oil Cleaner for Cars and Truck, 15 Oz, STP
High Milage Engine Flush Formula, Oil Cleaner for Cars and Truck, 15 Oz, STP

9 Best Engine Flush Products

There are lots of excellent engine flush products to choose from, and each one offers slightly different features and benefits. Read on to see the pros and cons of our top picks and their best features.

1. Liqui Moly 2037 Pro-Line Engine Flush

The Liqui Moly Pro-Line Engine Flush is easy to use without a machine, and thoroughly cleans any 4-stroke gasoline or diesel engine.


  • Gentle on the engine, yet works quickly
  • Won’t harm seals and other components
  • Safe for catalytic converters and non-metal materials
  • Easy to use without any special tools


  • Removes Ceratec and potentially other oil additives so you’ll need to re-add them

Liqui Moly engine flush is an easy way to remove debris from your engine through the oil system in both gasoline and diesel-powered vehicles. This gentle formula produced in Germany is easy to use even without an engine flush machine and works for all 4-stroke engines.

You’ll use Liqui Moly prior to an oil change to dissolve sludge and other residues and debris, which can help restore your engine’s full performance. This product also protects against corrosion of any unprotected metal surfaces and improves the combustion process inside the engine.

This product is fully compatible with all commercially available engine oils, and the Liqui Moly brand is known for its award-winning products.

2. Golden Touch 1698 Fast Flush Engine Flush

The Golden Touch Fast Flush Engine Flush replaces your engine oil entirely for a gentle yet effective cleaning without a lot of fuss.


  • Free from kerosene or mineral spirits
  • Suitable for all gasoline engines, both domestic and imported
  • Made in the USA


  • Requires an unused oil filter for cleaning which you replace again when you add new oil

Unlike some types of engine flush, Golden Touch Fast Flush is added to your engine once you have already drained the dirty oil from it. This large container is suitable for a single treatment and replaces the engine oil temporarily.

Once you’ve added this product to the crankcase, you’ll replace the dirty oil filter with a new one and allow the car to run for a few minutes.

This product isn’t an additive for engine oil like other products out there, and when the cleaning process is complete, you replace the used filter with a new one and add conventional engine oil as usual.

This petroleum-free product uses Butyl Cellosolve as it’s active ingredient, which gets suspended in 10W motor oil, so it’s gentle at flushing away debris and sludge without harming seals or other materials.

3. STP High Mileage Engine Flush Formula

The STP High Mileage Engine Flush Formula is highly concentrated, easily added to your oil, and ideal for vehicles with engine noise and mileage over 75,000 miles.


  • Specially formulated for engines over 75,000 miles
  • Safe for engine seals and all gasoline and diesel engines
  • Gentle enough to use during every oil change
  • Compatible with synthetic and conventional motor oil


  • Small bottle only enough for about one treatment

If you notice that your engine is noisier than usual, the STEP High Mileage Engine Flush Treatment can help quiet it down almost immediately. This product is simple to use and gets added to your existing engine oil to clean up any debris, sludge, or varnish in your engine that can wreak havoc on higher mileage vehicles.

This engine flush won’t harm the seals on your engine, and it’s gentle enough to use at every oil change. The super-concentrated formula actively removes deposits and is scientifically engineered for vehicles over 75,000 miles. You’ll only get a single treatment out of a bottle, most likely, but it’s inexpensive enough not to matter based on the glowing reviews from users.

4. WYNNS 51265 425ml Engine Flush

Wynns engine flush is an easy to use product that you add to your dirty engine oil to quickly clean out gunk from your engine, and prevent contamination of your new engine oil.

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  • Suitable for both gasoline and diesel engines
  • Easily added to the engine oil and current filter
  • Removes contaminants from vital parts and dissolves harmful solids


  • Only one treatment in each container

Wynns has a long-standing reputation for creating excellent quality products, and their engine flush is easy to add to your dirty engine oil prior to an oil change. To use this product to clean your engine, you’ll only need to run your vehicle for about 20 minutes and then continue with an oil change as usual.

Wynns engine flush gently cleans your engine and works on all gasoline and diesel-powered vehicles to dissolve solids and wash away stubborn sludge. This product also stops gunk from contaminating your new engine oil by thoroughly cleaning the internal parts without damaging seals or other components.

5. XADO Engine Oil System Cleaner with Anti-Carbon Effect

The XADO Engine Oil System Cleaner is an excellent option for engines that need a deep cleaning of their internal parts and ventilation system without using any special tools.


  • Helps restore piston mobility
  • Universally safe for all engines, including turbo engines
  • Removes carbon and other contaminants
  • Clears away debris from the crankcase ventilation system


  • May take longer to work than other treatments depending on your engine’s condition

XADO Engine Oil System Cleaner is a safe way to remove several different kinds of contaminants from your engine while also restoring the mobility of different moving parts such as pistons. This product is suitable for all engine types, including those that are turbo-charged.

This cleaner can remedy a number of issues as it cleans the internal parts of your engine, and it removes carbon that can cause unnecessary friction on surfaces. Using this product is easy as you can add it to your engine and allow it to idle for 10-15 minutes before performing an oil change.

6. BG EPR Engine Performance Restoration

The BG EPR Engine Performance Restoration tool is safe for use at each oil change and can boost your vehicle’s overall performance by removing damaging impurities.


  • Each can provides one treatment
  • Safe to use at each oil change or every 15,000 miles
  • Treats engines up to 6 liters


  • Not for engines with higher levels of built-up sludge

Using BG EPR Engine Performance Restoration is as easy as pouring it into your oil reservoir on your engine and running the engine on idle for 10 minutes at 1200RPM. With this engine cleaner, you’ll want to allow the oil time to cool after running the engine before draining it and doing an oil change.

One drawback to this product is that it won’t work as well with engines that have higher levels of built-up sludge as this product isn’t strong enough to remove that much contamination. It’s tricky to determine how much sludge there is in your engine, but if you’re looking for a product to use with your vehicle on a regular basis, this product is safe for use at each oil change.

7. Niteo Motormedic MFD1 Synthetic Motor Flush

The Niteo Motormedic MFD1 Synthetic Motor Flush is an ideal product for a quick engine cleaning right before an oil change, as it only takes five minutes.


  • Compatible with synthetic and conventional motor oil
  • Safe for turbo-charged engines and all other gasoline and diesel engines
  • Dissolves accumulated varnish, sludge, and gummy build-up


  • Not for engines with a high level of sludge build-up

The synthetic-based Niteo Motormedic MFD1 motor flush is compatible with all oil and engine types and uses synthetic-based oil to carry the active ingredients through your engine.

During this cleaning process, the solvents and detergents this product contains work to dissolve moderate amounts of varnish, gummy substances, and sludge in all areas of the engine it touches.

This product also helps with sticky piston rings but doesn’t damage seals as it cleans. This engine flush removes any debris it finds when you drain away the dirty oil, and the cleaning process only takes five minutes, so it’s easy to fit in right before an oil change.

8. Sea Foam SF-16 Motor Treatment

The Sea Foam SF-16 Motor Treatment is an excellent multi-purpose engine flush that you can add to your crankcase oil or fuel and still drive your vehicle as usual.


  • Cleans and lubricates with only one product
  • Uses 100% pure petroleum
  • Safe for all 2-stroke and 4-stroke gasoline and diesel engines
  • Dissolves oil deposits, fuel residue, and other gummy debris


  • Requires you to measure out ounces of product for each application

Sea Foam motor treatment has been a standard option for engine flushing for years, but this product can do so much more than remove debris. This product is safe for both 2-stroke and 4-stroke diesel and gasoline engines, and it’s also useful for stabilizing fuel. You can add this product to your crankcase oil or to your fuel.

Depending on how you add this product to your engine, you’ll be able to clean injectors, passageways, carb jets, and remove fuel residue in the fuel system. You can also remove oil deposits and lubricate intake valves and pistons. This motor treatment uses 100% pure petroleum as the carrier oil, and it’s registered with the EPA.

Sea Foam recommends that you add this motor treatment to your fuel every 3,000 miles or whenever you refuel. For engine oil, you can add this product 100-300 miles before an oil change and still drive your vehicle as usual.

9. CRC SX128 Salt Terminator Engine Flush

The CRC Salt Terminator Engine Flush is a must-have for any engine exposed to saltwater or freshwater either directly or through the air as both can cause corrosion inside and out.


  • Dissolves contaminants and leaves a protective coating behind
  • Multiple package sizes available (12 ounces, 32 ounces, and 1 gallon)
  • Suitable for engines exposed to saltwater and freshwater
  • Biodegradable formula


  • Using this product is more involved than other engine flushes

The CRC Salt Terminator Engine flush involves a more complicated process than other engine flushes, but this one features a unique formulation to handle contaminants outside of the usual dirt and sludge. With this product, you can remove calcium, salt, corrosion, carbon, and other deposits from boats, dive gear, RVs, trucks, motorcycles, and automobiles.

This product is available in different sizes so you can buy what you need and use it on anything exposed to saltwater or freshwater, including engines exposed to salty air or road salt. This product leaves behind a thin protective sheen that helps prevent further corrosion and build-up without affecting how the engine runs.

What is an Engine Flush?

An engine flush is a product that you can buy and add to your vehicle’s engine to remove debris from it internally. There is a bit of variety on what these products claim to accomplish within an engine, and many of them focus on the removal of sludge and deposits that settle in your engine and potentially cause issues over time.

Engine flush products are liquids that you add to your engine either through the oil or fuel, and how they work precisely depends mainly on their ingredients. The formulas between different types of engine flush are not always the same, and some require a greater quantity of solution than others to do the same job.

How much engine flush you need doesn’t necessarily say anything about the solution’s quality, but how much you need for a particular car may vary. The amount of engine flush you need may depend on its strength or the amount of contamination in your engine.

Should I Flush My Engine?

Engine flushing is a controversial issue at best, with pros and cons on each side of the argument. Some experts find engine flushing to be unnecessary maintenance, but others claim it can help you squeak out a few extra years from an older car.

Many individuals find engine flushes useful for older vehicles that have specific operation issues or that are close to no longer running. An engine flush can help an older car run better and remove the sludge that would otherwise continue to build up and make the car run worse. If the vehicle is currently not running, an engine flush is often not possible or helpful.

Short car trips can cause a build-up of carbon in your engine, and this type of material can cause symptoms like a drop in fuel mileage, or less of a peppy feel when you drive. If you see other signs like a “Change Oil” light coming on early or oil splatter on your hood’s underside, there may be some sludge build-up in your oil pan.

If you aren’t good about changing the oil on your car or if you’re making a lot of short trips or stop-and-go driving, you might be more likely to have sludge build-up in your car engine. Sludge may also build up in engines of cars that sit for long periods of time, and finding the best engine flush can help remedy this issue quickly and inexpensively.

Very tiny particulate matter in motor oil can leave deposits in parts of your vehicle’s engine that are difficult to remove thoroughly without an engine flush. If you remove your oil cap and can clearly see a decent amount of tiny particulate matter, you might want to consider an engine flush.

How Often Do Engines Need Flushing?

Many manufacturers do not recommend engine flushing as they feel it will clog vital parts of the engine and ultimately make the vehicle perform more poorly than before.

Exhaustive tests of various car engines have revealed that engine flushing isn’t a recommended step of long-term maintenance, and regular flushing doesn’t extend your vehicle’s longevity when performed regularly or early on in its life.

However, if your vehicle is quite old, not running well, or generally not going to last much longer anyway, flushing the engine can get you some valuable time. There are also several car owners who swear that flushing their engine allowed them to drive their vehicle longer without expensive repairs, and there are many reviews and anecdotal evidence of this online.

Some sources recommend flushing your engine every 5,000 or 10,000 miles, but modern engines should be able to go 35,000 or more before flushing. Other sources insist that newer vehicles have more advanced engine technology that no longer needs flushing, and using engine flush on these vehicles may end up harming the engine more than it helps.

Benefits to Engine Flushing

The primary benefit of an engine flush is to remove any built-up gunk that might be causing your engine to make noise or otherwise operate below its optimal level. How your engine behaves will vary based on the number of contaminants it contains and what else is mechanically wrong with the vehicle.

These deposits of varnish, sludge, dirt, and other debris restrict how much oil flows through your engine, and narrowed passes might cause the engine to overheat, run with far less power, or otherwise make abnormal sounds.

If you’ve recently bought an older car that has an unknown maintenance record, flushing the engine is a cheaper alternative to major repairs and can also remove debris that collects when a vehicle sits for a prolonged period.

Flushing the engine also helps to keep the new oil you put in clean. Most engine flushing products get added to the dirty engine oil, and you allow the engine to run for a set amount of time to circulate the cleaner and allow it time to work.

After this time is over, you drain the dirty oil away and all of the contaminants with it, so the new oil is much cleaner than it would be without an engine flush. If you didn’t flush the engine first, the new oil would be able to pick up any leftover debris and circulate it through your engine and potentially cause more damage.

Engine flush also cleans the internal parts of your engine that it comes in contact with, and in very old cars, the piston rings, valves, and some other parts need extra attention. A clean engine will run more smoothly and may also have greater fuel efficiency.

Drawbacks to Engine Flushing

One consistently voiced drawback to engine flushing is that there is a risk that it could further damage the engine by kicking up old debris and causing it to plug various screens and parts of the engine. Oil filters pick up particles down to 25 microns, but smaller bits than this will slip through and can settle anywhere they like.

Some strong engine flushing products can also damage seals or the internal parts of the engine, and this may result in leaks. Removing gunk can also expose tiny cracks in the engine, near the seals, or in other locations, and this can also result in leakage.

Another drawback is that typically you can only use these products when you will also change the oil in the vehicle as you can’t drive your car once you add engine flush to the oil or fuel. Some products allow you to drive a specific number of miles, but it’s more likely you’ll damage the engine.

Engine Flushing and Safety

Engine flushing products are usually solvents and are typically flammable and harmful to humans and animals. Keep any children or animals away from the area where you are working when using engine flush, and consider wearing gloves to protect your skin.

Some of the chemicals used in engine flush can absorb through the skin, and while a small amount is not typically harmful, it could cause skin irritation. You’ll also want to use engine flush in a very well ventilated area as the vapors can harm your skin, lungs, and eyes if inhaled or allowed to build up in your area.

It’s also an excellent idea to wear protective eye goggles when using this product, and protective clothing as needed to ensure your skin is covered and protected. If you swallow or otherwise ingest an engine solvent, you should immediately contact poison control as different solvents require unique treatment.

Repeated exposure to engine flush can cause lung damage, skin dryness, and skin cracking. If you spill engine flush, you can soak it up with vermiculite, dirt, or sand and seal it in a container before disposing of it properly as it is considered hazardous waste.

Engine Flush FAQ

There are a number of different engine flush products to choose from, and our list of frequently asked questions can help you narrow down the options until you find the right one for you.

How do engine contaminants harm my engine?

Depending on the contaminant in question, your engine might make more noise in general, or these might be a distinct ticking sound. It’s also possible for an engine to lose its peppy feel, or otherwise not operate at full power.

Some engines will overheat or run less efficiently, but the symptoms you see will vary widely based on any other mechanical problems with the engine.

Should I choose a synthetic or petroleum-based engine flush?

Some engine flushes feature a carrier oil that is synthetic or petroleum-based, and which one you should use will depend on a few factors.

Many engine flushes are compatible with all kinds of oil, so it doesn’t matter what carrier oil they contain, but a select few feature unique formulas to treat high mileage vehicles. These engine flushes often feature a synthetic carrier oil that may or may not be compatible with traditional motor oil.

How much engine flush do I need?

How much engine flush you need will largely depend on the size of the engine you want to clean and how much oil or fuel that product says it can treat.

Most engine flush products treat up to 5 or 6-liter engines, but a few of these engine flushes you’ll measure out and premix them with fuel.

Once you’ve picked an engine flush product, you’ll want to read the instructions to determine how much you need carefully, but typically one can, or bottle, is sufficient for a single treatment.

Final Thoughts

If you have an older car that isn’t running well and you suspect a build-up of contaminants in the engine, a quick engine flush followed by an oil change is often worth a try. While engine flushing is controversial for newer cars, it may help an older car run longer without expensive repairs.

Even the best engine flush is not a permanent solution, and finding a good quality engine flush product is crucial. Engine flushes come in different formulas, so you’ll want to read the package and find one that is the proper strength for your particular engine and suspected sludge problem.

Otherwise, an engine flush can remove dirt, debris, varnish, and sludge, so your engine runs better and with less noise. These products can also help with sticky pistons and lubricate as they clean.


Brett Gordon

The engine behind editing at DigMyRide and the brains behind its build. During the day, Brett is a thirty-something dude from SoCal climbing the corporate ladder, but by night, he spends his time contributing to the online world of automotive tech & trends.