6 Best Solvent to Clean Engine Parts 2025 [Fast & Heavy-Duty]

We get our hands dirty so you don’t have to. Cleaning engine parts is a messy job, but the right solvent makes it easy. The wrong one can waste your money and time, or even damage your parts.

Everyone claims their product is the best. We did not believe the ads. We bought the top six products ourselves and tested them on the grimiest parts we could find. I spent days spraying, scrubbing, and rinsing. I read thousands of user reviews to see what real people think.

This guide is the result of all that work. I will show you what each product can and cannot do. We will tell you which one is the best value. I will tell you which one is the strongest. I will help you find the perfect cleaner for your exact needs.

This is not a sales pitch. This is an honest report from our garage to yours.

How We Tested: Our Fair Method for Unbiased Results –

We wanted to test every cleaner the same way. This is the only way to be fair. We did not just spray them on and take a guess. We made a strict plan and followed it for every single product.

Our Testing Protocol and Equipment:

We set up a test area in a well-ventilated garage. The temperature was a steady 65 degrees Fahrenheit. We controlled the environment to keep our results consistent.

We collected a set of very dirty parts from old engines:

• A valve cover: Caked with thick, black oil sludge.
• A transmission pan: Covered in grimy, sticky grease.
• An exhaust manifold: Black with baked-on carbon.
• A carburetor: Gummed up with old fuel varnish.

For each test, we did the same thing:

1. Application: We sprayed the solvent on a dry part. We used the same amount for each test.
2. Dwell Time: We timed how long we let the product sit. We noted how quickly it started to break down the grease.
3. Agitation: We used the same nylon brush to scrub the part. We counted the number of strokes needed to clean it.
4. Rinsing: We used a pressure washer set to the same pressure. We measured how much water it took to rinse the part completely clean.
5. Inspection: We looked at the part under a bright light. We checked for any leftover residue, film, or damage to the metal.

How We Measured Performance:

What We Tested	How We Did It	Tool We Used	What We Looked For
Cutting Power	Time for grease to melt and drip	Stopwatch	Seconds until grease falls apart
Residue	Rinse with water and inspect	Eye, bright light	Any oily film left behind
Material Safety	Spray on aluminum and rubber	Eye inspection	Damage like discoloration or swelling
Ease of Rinse	Measure water to rinse clean	Water flow meter	Gallons of water used

How We Read User Reviews For You:

We did not just rely on our own tests. We believe the experiences of thousands of users matter. For each product, we read hundreds of reviews.

We looked for patterns. What did people love? What did they complain about again and again? This helped us understand the long-term pros and cons that you might not see in a short test.

A product might work great for us once, but what if it clogs sprayers over time? Users will tell us that. We combined their real-world experience with our controlled test data.

The Engine Degreasers: A Quick Buyer’s Guide –

Before we get to the reviews, let’s talk about what you are buying. Not all cleaners are the same. Knowing the difference will help you choose the right one.

Key Words Explained:

• Solvents: These are the chemicals that actually dissolve the grease and gunk. Think of them like the soap for your dishes.
• Emulsifiers: These chemicals grab onto the grease that the solvent breaks loose and hold it in the water. This lets you rinse it all away. Without them, the grease would just stick back on the part.
• Concentrates: These are powerful formulas that you must mix with water before using. One gallon can make many gallons of cleaner. They are cheaper in the long run but require an extra step.

Different Types of Cleaners:

• Petroleum-Based: The old-school, powerful stuff. They work very well but can be harsh. They might be flammable and can damage rubber or plastic if you are not careful.
• Bio-Solvent: A newer kind of cleaner. They are often made from natural materials. They are usually safer for you and the environment. Many are non-flammable and less harsh on sensitive parts.
• Water-Based: These use water as the main ingredient. They are often gentle and safe. Concentrates are usually water-based.

5 Things to Think About Before You Buy:

1. What are you cleaning? A greasy engine block is different from a delicate carburetor inside. A shop floor is different from a bicycle chain. Match the cleaner to the job.
2. What is the part made of? Is it aluminum? Some cleaners can discolor or damage aluminum. Is there rubber or plastic? Harsh chemicals can make these materials brittle or soft.
3. How will you use it? Do you want to just spray it on and rinse it off? Or are you okay with scrubbing? Do you need to soak parts in a bucket?
4. Is safety important? Will you use it in a closed space? Look for low-odor, non-flammable formulas. Do you care about the environment? Look for biodegradable and safer certifications.
5. What is the real cost? A cheap bottle that is not concentrated might be more expensive than a concentrate you mix yourself. Always think about cost per use.

At a Glance: Our Top Picks Compared –

After all our testing, here is a quick look at how all six products stack up against each other. We ranked them based on their performance in our tests, their value, and user feedback.

Product Name	User Rating	Key Strength
Simple Green Industrial	4.7	Unbeatable Value
WD-40 Specialist	4.4	All-Around Safety
3D Grand Blast	4.6	Pro Power, Safe on Paint
Zep Industrial Purple	4.6	Maximum Strength
Northwest Enterprises	4.5	Ultrasonic Specialist
Qucship Ultrasonic	4.9	Budget Ultrasonic

Best Solvent to Clean Engine Parts: 6 Automotive Engine Degreasers Review:

Now, let’s get into the details. We will take a close look at each product one by one. We will tell you exactly what we found, both the good and the bad.

#01. Simple Green Industrial Cleaner: The Best Overall Value

• User Rating: 4.7 from 15,935 reviews
• Best For: Anyone who needs a versatile, cheap cleaner for almost anything.

The first thing you notice is the price. For less than eleven dollars, you get a giant bottle. But the real magic is on the label: this one bottle can make over 127 gallons of cleaner.

This makes it the cheapest option by a very large margin. It has the highest number of user reviews, which tells us it is a trusted, popular choice.

What We Liked:

• Extremely low cost per gallon.
• Very versatile – can be used on engines, floors, tools, and more.
• Huge number of positive user reviews prove it works.
• Biodegradable formula.

What We Didn’t Like:

• The sassafras smell is strong and not everyone likes it.
• It is not the most powerful option for the toughest, baked-on grease.

Specs and Features:

• Brand: Simple Green
• Form: Liquid Concentrate
• Scent: Sassafras
• Uses: Carpet, Sink, Tile, Upholstery, Floors, Engines
• Feature: Biodegradable

This product is not just for cars. The brand says you can use it on carpets and sinks too. This makes it a great all-purpose cleaner for your whole garage or shop. Being biodegradable is a nice plus for the environment.

Performance Tested: Our Hands-On Results

We mixed it according to the directions for a tough job. We sprayed it on our oily valve cover. It took about 5 minutes to start breaking down the thick sludge. It required a bit more scrubbing than the dedicated automotive degreasers.

However, once we scrubbed, the grease came off easily. It rinsed away with a moderate amount of water and left no visible residue. It worked perfectly on the transmission pan and shop floor.

Test Verdict: It works very well for most jobs. For the absolute worst grease, you might need to let it sit longer or scrub a bit more. But for 90% of tasks, it is more than powerful enough.

User Feedback: What 15,935 People Say –

People love this stuff. The most common words in reviews are “value,” “versatile,” and “works great.” Many people say they use it for everything from cleaning their engine to mopping their garage floor. The few complaints are almost always about the smell.

The Verdict: Who Should Buy This?

Buy this if: You want one cleaner that can do almost everything in your garage. You are on a budget and want the most value for your money. You need to clean large areas like floors.

Skip this if: You only work on cars and need the most powerful, dedicated automotive degreaser. You cannot stand the sassafras scent.

#02.WD-40 Specialist Cleaner & Degreaser: The Safest All-Rounder

• User Rating: 4.4 from 1,936 reviews
• Best For: People who want a safe, effective, ready-to-use spray for many surfaces.

This product is ready to use right out of the bottle. You do not need to mix it with water. This is very convenient. The most impressive thing is its safety profile. It is certified by the U.S. EPA Safer Choice program.

This means it is made with ingredients that are safer for people and the environment. It also says it is safe on glass, aluminum, and metal without causing damage.

What We Liked:

• Very safe to use on many materials.
• Ready-to-use, no mixing required.
• Non-flammable and low odor.
• EPA Safer Choice certification.

What We Didn’t Like:

• More expensive per gallon than concentrates.
• Not quite as strong as the most aggressive concentrates.

Specs and Features: What You Get

• Brand: WD-40 Specialist
• Form: Liquid (Ready-to-use)
• Scent: Unscented
• Uses: Glass, Engines, Floors, Equipment
• Feature: Biodegradable, Non-Toxic

The “Specialist” line is WD-40’s professional series. This cleaner is designed to be a professional-grade product. Its ability to clean glass without etching it is a unique and useful feature.

Performance Tested: Our Hands-On Results

We sprayed it directly on the grimy transmission pan. It began cutting through the grease immediately. It required very little dwell time—only about 2-3 minutes and wiped away with minimal scrubbing.

We used it on a grease-smeared shop window, and it worked perfectly, leaving no streaks or damage. On our aluminum part, it cleaned effectively without causing any discoloration or white residue, which some cleaners do.

Test Verdict: This is a fantastic “quick and safe” option. It is not the absolute most powerful, but it is very effective and its safety makes it worry-free. You can use it on almost anything without fear of damage.

User Feedback: What 1,936 People Say

Users consistently praise its safety and effectiveness. They love using it on engines, driveways, and even kitchen appliances. The phrase “no damage” appears often. Some users note that for decades-old, caked-on grease, they need a heavier-duty product.

The Verdict: Who Should Buy This?

Buy this if: You want a convenient, ready-to-use spray. You clean a variety of surfaces and need a product that is safe on all of them. You work in a space where fumes and flammability are a concern.

Skip this if: You are only cleaning extremely heavy machinery and need the strongest solvent available. You want to buy a concentrate to save money.

#03. 3D Grand Blast Engine Degreaser: The Best for Car Enthusiasts

• User Rating: 4.6 from 712 reviews
• Best For: People who detail cars and want a powerful yet safe cleaner for engine bays.

This product is made by a company for “car guys.” It is designed specifically for cleaning cars. It promises heavy-duty power that is still safe on painted surfaces, plastic, and rubber.

This is important because your engine bay is full of these sensitive materials. You do not want a cleaner that will ruin your wiring or make your plastic covers look faded.

Pros:

• Powerful cleaning that is safe for delicate engine bay parts.
• Fast-acting formula; works quickly.
• Low odor.
• Made in the USA.

Cons:

• It is one of the more expensive options for a gallon.
• It is specialized for automotive use, not as versatile for other jobs.

Specs and Features: What You Get

• Brand: 3D
• Form: Liquid
• Scent: Unscented
• Uses: Engine, Floor
• Feature: Natural

The word “Natural” in the features suggests it uses naturally-derived solvents. This often means it is safer for the user and the environment compared to harsh petroleum solvents.

Performance Tested: Our Hands-On Results

We tested this on the engine bay of a dirty car. The goal was to clean the grease without harming the painted valve cover, rubber hoses, and plastic covers. We sprayed it on and it immediately began dripping down, pulling grease with it.

After 5 minutes, most of the grease was already dripping off. We used a soft brush for a light scrub. The result was a very clean engine bay with no faded plastic or damaged rubber. It rinsed off easily with a light spray of water.

Test Verdict: It lives up to its promise. It is powerful enough for engine grime but gentle enough for the details. It is the best product we tested for making an engine look detailed and clean, not just degreased.

User Feedback: What 712 People Say

Reviews from users are filled with words like ” amazing,” “no scrubbing,” and “safe on everything.” Car detailers and professional mechanics love this product for its balance of power and safety. The higher price is the most common drawback mentioned.

The Verdict: Who Should Buy This?

Buy this if: You are cleaning your car’s engine bay and want fantastic results without damaging any components. You are a car detailer or enthusiast who cares about the final look.

Skip this if: You need to clean industrial machinery or garage floors. You are on a tight budget.

#04. Zep Industrial Purple Cleaner: The Heavy-Duty Powerhouse

• User Rating: 4.6 from 1,150 reviews
• Best For: Professional mechanics and shops dealing with the toughest industrial grease.

Zep is a brand known in the professional cleaning world. This product is a serious tool for serious jobs. It comes in a massive 5-gallon pail. The key fact is that it is a concentrate; that one pail can make up to 128 gallons of cleaner. This is an industrial-grade product designed for constant use in a busy shop.

What We Liked:

• Incredible cutting power on the thickest, caked-on grease.
• Extreme value per diluted gallon for high-volume users.
• Proven reputation with professionals.

What We Didn’t Like:

• High upfront cost for the large pail.
• Can be harsh on sensitive metals like aluminum if not rinsed thoroughly.
• Not designed for delicate parts or casual use.

Specs and Features: What You Get

• Brand: Zep
• Form: Liquid Concentrate
• Scent: Unscented
• Uses: Engine, Floors
• Feature: Concentrated

This is a no-frills, powerful formula. The “Purple” in the name often indicates a high-performance industrial cleaner. It is built for one thing: destroying grease and grime on hard surfaces like concrete floors and steel machinery.

Performance Tested: Our Hands-On Results

We mixed it to the recommended strength for heavy grease. We used it on the baked-on exhaust manifold, which was our toughest test. The results were impressive. It cut through the carbon crust faster than any other product we tested. It required almost no scrubbing; the grease just melted away.

However, we also tested it on a bare aluminum bracket. We noticed that if we let it dry, it left a slight white residue that required extra rinsing to remove. This confirms it is powerful but requires care on softer metals.

Test Verdict: For raw, unadulterated cleaning power on steel and iron, Zep Purple is the king. It is the most effective cleaner we tested on the absolute worst grime. But with great power comes great responsibility: you must use gloves and rinse it completely.

User Feedback: What 1,150 People Say

Professional mechanics and shop owners dominate the reviews. They consistently call it “the best,” “strongest,” and “only product that works.” The large size and concentrate form are seen as major benefits for their business. Warnings about its strength—”wear gloves” and “rinse well”—are common in the reviews.

The Verdict: Who Should Buy This?

Buy this if: You run a professional auto or machine shop. You regularly deal with the kind of grease that defies other cleaners. You need to buy in bulk and want the best cost per gallon.

Skip this if: You are a DIYer cleaning your car engine a few times a year. You work with aluminum or other sensitive metals. You don’t have a place to store a 5-gallon pail.

#05. Northwest Enterprises Ultrasonic Solution: The Specialist’s Choice

• User Rating: 4.5 from 2,029 reviews
• Best For: Anyone using an ultrasonic cleaner to restore carburetors and small engine parts.

This is not a spray-and-rinse product. This is a specialized chemical designed for one purpose: to be used in an ultrasonic cleaning machine. These machines use sound waves to create tiny bubbles that scrub parts clean.

This solution is engineered to make that process more effective on automotive gunk like fuel varnish and carbon deposits.

What We Liked:

• Specifically formulated for ultrasonic cleaning.
• Huge number of reviews (2,029) shows it’s a trusted product in its niche.
• Safe on a wide range of metals, including aluminum.
• Removes internal varnish that sprays can’t touch.

What We Didn’t Like:

• Useless without an ultrasonic cleaner.
• Not for cleaning large parts or engines.

Specs and Features: What You Get

• Brand: NORTHWEST ENTERPRISES
• Form: Liquid Concentrate
• Scent: Unscented
• Uses: Automotive Engine Parts Cleaning
• Item Volume: 1 Gallon

The product specs highlight its targeted use. It is safe on metals like aluminum, brass, and copper, which is critical for delicate carburetor parts. It is also free of harsh chemicals like phenols and nitrates.

Performance Tested: Our Hands-On Results

We placed a gummed-up carburetor jet into our ultrasonic cleaner filled with a diluted mix of this solution. We ran the machine for 20 minutes. The result was stunning.

The jet was completely clean, with all the internal varnish removed. The tiny passages were clear. We tried the same with a standard degreaser, and it did not work nearly as well. The Northwest solution was clearly designed for this specific task.

Test Verdict: For its intended job—cleaning in an ultrasonic tank—it is exceptional. It works significantly better than trying to use a general-purpose degreaser for this purpose. It is the professional’s choice for a reason.

User Feedback: What 2,029 People Say

Users are almost all people who rebuild small engines and carburetors. The reviews are filled with phrases like “cleaned my carburetor like new,” “worth every penny,” and “must-have for ultrasonic cleaners.” The high review count for such a specialized product is a powerful testament to its effectiveness.

The Verdict: Who Should Buy This?

Buy this if: You own an ultrasonic cleaner and work on carburetors, fuel injectors, or other small, intricate engine parts. You want the best solution for that machine.

Skip this if: You do not own an ultrasonic cleaner. You need a cleaner for large parts or general spray-on applications.

#06. Qucship Ultrasonic Solution: The Budget Concentrate

• User Rating: 4.9 from 14 reviews
• Best For: Ultrasonic cleaner users on a budget who want a highly concentrated formula.

Like the Northwest solution, this product is only for use in ultrasonic cleaners. Its main claim is that it is an “8X Concentrate,” meaning one gallon makes 8 gallons of ready-to-use solution. This makes it a cheaper option per gallon than many competitors.

What We Liked:

• Very low cost per diluted gallon.
• High concentration means it takes up less storage space.
• High user rating (4.9), though from a small pool.

What We Didn’t Like:

• A very low number of reviews (only 14) makes it hard to verify long-term performance.
• Lacks the proven track record of the Northwest Enterprises solution.

Specs and Features: What You Get

• Brand: Qucship
• Form: Liquid Concentrate
• Scent: Unscented
• Uses: Automotive Engine Parts Cleaning
• Material Feature: Unscented

The specs are very similar to the Northwest solution. It also claims to be safe for all metals. The key difference is the marketing around its concentration level.

Performance Tested: Our Hands-On Results

We repeated the carburetor jet test with the Qucship solution, diluted to the same strength as the Northwest solution. It performed well. The jet came out clean and the internal passages were clear. In a blind test, we would be hard-pressed to notice a major difference in cleaning power between the two on this specific task.

Test Verdict: It cleaned our test part effectively. Based on our single test, it works as advertised. However, the extremely low number of user reviews is a concern. The Northwest solution has over 2,000 reviews proving its reliability over time. With Qucship, you are taking more of a chance on an unproven product, even if the initial results seem good.

User Feedback: What 14 People Say

The few reviews it has are very positive, hence the 4.9-star rating. Users say it works well and is a great value. However, 14 reviews are not enough to identify any potential patterns of failure or issues that might appear later.

The Verdict: Who Should Buy This?

Buy this if: You are on a very tight budget and the cost per gallon is your absolute main concern. You are willing to try a newer product with less feedback.

Skip this if: You rely on your ultrasonic cleaner for professional work and need a proven, reliable solution. You prefer to buy products with a long history of positive reviews.

Head-to-Head Comparisons:

Now that we have reviewed each product alone, let’s see how they compare directly against each other in key areas.

Zep Industrial vs. Simple Green: The Concentrate Showdown –

Both are concentrates, but they are designed for different worlds.

• Cleaning Power: Zep wins. Its formula is simply more aggressive and faster on industrial-grade grease.
• Versatility: Simple Green wins. You can use it on engines, floors, carpets, and more. Zep is really for hard surfaces and heavy grease.
• Material Safety: Simple Green wins. It is generally safer on a wider variety of materials, including sensitive metals and plastics.
• Value: It’s a tie, depending on use. For a home user, Simple Green’s $10 bottle is the better value. For a shop burning through cleaner, Zep’s cost-per-gallon at scale is unbeatable.

The Bottom Line: Choose Zep for maximum power in a professional setting. Choose Simple Green for all-purpose use at home.

Value Showdown: Best Ready-to-Use Degreaser

This compares the convenience of a ready-to-use spray versus the value of a concentrate.

• WD-40 Specialist (Ready-to-Use): You pay for convenience. At $15.36 per gallon, it’s more expensive per use, but you can just grab it and spray. It’s also the safest option.
• Simple Green (Concentrate): You pay less for more work. For $10.98, you get over 127 gallons of cleaner. You have to mix it yourself, but the savings are enormous.

The Bottom Line: If your time is valuable and you clean often, the WD-40 Specialist is a great buy. If you want to save as much money as possible and don’t mind mixing, Simple Green cannot be beaten.

Beyond the Basics: Accessories You Will Need –

Using these cleaners right requires a few simple tools. Here is what we use and recommend:

• Spray Bottles: For applying concentrates you’ve mixed. Get a few with different spray patterns (stream vs mist).
• Parts Cleaning Brushes: A set with stiff bristles for tough grease and soft bristles for delicate parts.
• Safety Glasses: Always. Chemicals can splash back.
• Nitrile Gloves: Protect your hands from harsh chemicals and grease.
• Parts Wash Tray: A simple plastic tray to soak parts and contain the mess.

Maintenance and Care Guide –

Taking care of your supplies is simple but important.

• Storage: Keep all containers tightly sealed. Store them in a cool, dry place out of direct sunlight. This keeps the chemicals from breaking down.
• Disposal: Never pour used degreaser or dirty solvent down a street drain or into the soil. Check your local rules for hazardous waste disposal. Many communities have a drop-off location.
• Tool Care: After using a concentrate, rinse your spray bottle and brushes with clean water to prevent the nozzles and bristles from getting clogged with dried chemical.

Frequently Asked Questions (FAQs)

Q1. What is the best way to clean an entire engine bay?

Answer: For a full engine bay, we recommend 3D Grand Blast. Our tests showed it has the perfect balance of power to cut through grease and safety for all the plastics, rubber hoses, and painted surfaces under the hood.

Spray it on, let it sit for 5-10 minutes, agitate with a soft brush, and rinse with a light spray of water.

Q2. I have an old lawnmower carburetor that is full of gunk. What should I use?

Answer: You need an ultrasonic cleaner and a solution like Northwest Enterprises. Spray-on degreasers can’t clean the tiny internal passages. An ultrasonic cleaner with the right solution is the only way to get it fully clean without damaging it.

Q3. Is it safe to pressure wash my engine after using degreaser?

Answer: Yes, but be careful. Avoid spraying directly at electrical components like the alternator, ignition coils, and sensors. Cover them with a plastic bag if you can. Use a wide-angle spray pattern instead of a focused, high-pressure stream to force water into seals.

Final Verdict: Our Top Recommendations for Every Need

After weeks of testing, measuring, and reading, we can give you our final picks. The best product depends entirely on what you need it for.

Overall Best / Best Value:

Simple Green Industrial Cleaner. The data does not lie. Its incredible versatility, ultra-low price, and massive number of positive reviews make it the best choice for most people. It might not be the absolute strongest, but it is strong enough for almost every job you have in your garage, and it will save you a lot of money.

Best Ready-to-Use / Safest Formula:

WD-40 Specialist Cleaner & Degreaser. If you want to grab a bottle and start cleaning without any mixing, this is the one to buy. Its EPA Safer Choice certification and proven safety on all types of surfaces mean you can use it without worry. It is perfect for quick jobs and general cleanup.

Best for Automotive Enthusiasts:

3D Grand Blast. If your goal is a showroom-clean engine bay, this is your product. It is specifically designed for car people who care about the details. It provides professional-level cleaning power without the risk of damaging your expensive car’s components.

Best for Ultrasonic Cleaning:

Northwest Enterprises Solution. For the specialized job of cleaning carburetors and small parts in an ultrasonic tank, the proven track record of Northwest Enterprises makes it the reliable choice. With over 2,000 reviews, you know it works and will not let you down.

No matter what you choose, you can be confident that these products have been tested thoroughly. We hope this guide helps you cut through the grease and the marketing hype to find the perfect cleaner for your shop. Happy cleaning

Last Updated on October 22, 2025 by Rogers Weber

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