Drivers often search for a reliable way to clear sludge and deposits without opening the engine, and Liqui Moly offers two strong contenders for that task: Engine Flush Plus and Pro-Line Engine Flush.
Each product targets a different level of contamination, and both deliver distinct benefits that suit different maintenance habits, vehicle conditions, and performance goals. Engine Flush Plus fits routine servicing because it supports engines that show moderate wear or early signs of buildup.
It cleans quickly, protects sensitive components, and prepares the engine for fresh oil with improved efficiency. Pro-Line Engine Flush steps into a more aggressive role, tackling hardened deposits and heavy sludge inside high-mileage or neglected engines
Mechanics often reach for this formula because it produces deeper internal cleaning and restores smooth operation in engines that demand stronger treatment.
Drivers gain the most value by understanding how each formula behaves and choosing the right option for specific engine needs.
Liqui Moly Engine Flush Plus vs Pro Line
Engine flush products help remove sludge, dirt, and deposits from inside the engine. Clean oil passages. Better flow. Better performance. Liqui Moly offers two popular options: Engine Flush Plus and Pro-Line Engine Flush.
Both serve the same purpose, yet each product has its own style, strength, and use case. The sections below break everything down in a clear, simple way.
Liqui Moly Engine Flush Plus
Product Details
Liqui Moly Engine Flush Plus comes in a 300 ml bottle. The price sits around 16 dollars. The product works with most internal-combustion vehicles and fits a wide range of engines. The viscosity label on the bottle shows 15W-40.
The formula suits standard engine cleaning before an oil change. Drivers use it to dissolve light to moderate sludge and to free up old deposits. The compact size works well for small to mid-size cars.
The additive flows through the engine oil system during a short idle period. The formula targets dirt without harming seals. The goal stays simple: clean the inside of the engine so new oil performs better.
Product Details
Formula Style
Flush Plus uses a mild detergent formula. It targets common dirt but keeps the cleaning strength moderate.
Fit Type
Works with almost all gasoline and diesel vehicles. Universal fit.
Bottle Size
300 ml bottle made for single use.
Key Differences
Oil Type
Flush Plus lists 15W-40 on the label. This reflects compatibility with common oil weights used in older and mid-range engines.
Viscosity Options
Only one size and one viscosity marking.
Additive Package
Designed with mild detergents. Suitable for light sludge removal. Safe for regular cleanouts.
Recommended Use Cases
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Routine cleaning
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Older engines with mild buildup
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Small cars with shorter oil capacity
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Drivers who want gentle cleaning without strong solvents
Performance Comparison
Engine Protection
Flush Plus clears basic dirt so oil can protect moving parts more effectively. Clean channels improve oil flow.
Fuel Efficiency
A cleaner oil circuit can reduce drag inside the engine. Small gains become possible.
Mileage Longevity
Cleaner internals support steady long-term operation. The effect is mild but helpful.
Cold-Start Performance
A cleaner system allows fresh oil to circulate faster during cold starts.
High-Temperature Stability
The mild formula handles heat well during the short idle cycle. It does not stress seals or metal surfaces.
Product Options & Specs
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Brand: Liqui Moly
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Volume: 300 ml
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Fit Type: Universal
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Viscosity label: 15W-40
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Packaging: Plastic bottle
Pros and Cons
Pros
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Safe for seals
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Mild cleaning action
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Good for regular maintenance
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Easy to use
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Works with most cars
Cons
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Not as strong as Pro-Line
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Smaller bottle
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May not remove heavy sludge
Liqui Moly Pro-Line Engine Flush
Product Details
Liqui Moly Pro-Line Engine Flush comes in a 500 ml metal can. The formula carries stronger detergents designed for deep cleaning. The price sits around 20 dollars. The viscosity label shows 5W-40.
The product fits buses, trucks, and cars that require heavier cleaning. Many drivers use this flush for engines with long service intervals or engines that show signs of sludge.
Pro-Line targets heavy deposits. The mixture cleans quickly. It stays neutral to seals and keeps catalytic converters safe. The can design feels more industrial and supports professional use in workshops.
Product Details
Formula Style
Pro-Line uses a stronger formula with advanced detergents. It targets both light and heavy buildup.
Fit Type
Works with gasoline and diesel engines. Good for larger vehicles.
Can Size
500 ml metal can. Suitable for bigger oil capacities.
Key Differences
Oil Type
Label shows 5W-40. This indicates compatibility with modern engines that run thinner oils.
Viscosity Options
Single viscosity marking.
Additive Package
Stronger detergents. Aimed at deep cleaning and heavy sludge removal.
Recommended Use Cases
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High-mileage engines
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Engines with poor maintenance history
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Diesel engines with thick deposits
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Workshop-level cleaning before major service
Performance Comparison
Engine Protection
Pro-Line removes heavy sludge that may block oil flow. Clean oil passages reduce wear.
Fuel Efficiency
A deep-cleaned engine often runs smoother. Lower friction can improve fuel economy.
Mileage Longevity
A heavy flush extends engine life by removing harmful buildup.
Cold-Start Performance
Deep cleaning allows new oil to reach critical parts faster during cold starts.
High-Temperature Stability
Strong detergents hold up well under heat. Safe for short idle cycles during flushing.
Product Options & Specs
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Brand: Liqui Moly
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Volume: 500 ml
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Fit Type: Universal
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Viscosity label: 5W-40
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Flash Point: 63°C
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Packaging: Metal can
Pros and Cons
Pros
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Strong cleaning power
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Works well on high-mileage engines
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Safe for seals
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Professional-grade strength
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Good for heavy sludge
Cons
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Higher price
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May be too strong for very old engines with weak seals
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Might be unnecessary for clean engines
Details Comparison for Liqui Moly Engine Flush Plus vs Pro Line
Flush Plus fits average drivers who want simple cleaning. The formula stays mild and protects older engines with light residue. The small bottle suits cars with low oil capacity.
Pro-Line fits engines with heavy deposits or long oil intervals. This option brings stronger cleaning and works well in professional settings. The bigger can suits trucks, buses, and cars with larger oil systems.
Flush Plus cleans lightly and safely. Pro-Line cleans deeply and aggressively. The right choice depends on engine condition and cleaning needs.
Comparison Table
| Feature | Engine Flush Plus | Pro-Line Engine Flush |
|---|---|---|
| Bottle Size | 300 ml | 500 ml |
| Viscosity Label | 15W-40 | 5W-40 |
| Cleaning Strength | Mild | Strong |
| Best For | Light sludge | Heavy sludge |
| Vehicle Type | Small & mid-size cars | Cars, trucks, buses |
| Seal Safety | High | High |
| Price | Lower | Higher |
| Additives | Basic detergents | Advanced detergents |
FAQs
Does either product harm engine seals?
No. Both stay neutral to seals.
Can both products work with gasoline and diesel engines?
Yes. Both support all common internal-combustion engines.
How long should the engine idle with these products?
Most drivers idle for 10–15 minutes. Always follow the label.
Should both products be used before every oil change?
Not always. Flush Plus suits regular maintenance. Pro-Line suits heavy-duty cleaning.
Can these products fix engine noise?
They may reduce noise if sludge affected oil flow. They cannot fix mechanical wear.
Which One Should You Choose?
Use Engine Flush Plus if your engine stays in good shape and only needs routine cleaning. Light deposits. Smooth running. Budget-friendly choice.
Use Pro-Line Engine Flush if your engine shows signs of heavy buildup, long oil gaps, or high mileage. Strong cleaning. Deep deposit removal. Better for diesel engines and large vehicles.
Both products clean the engine. The correct choice depends on how dirty your engine is and how strong a flush you need.