Purpose and Specifications

LIQUI MOLY 21649 Fuel Protect Diesel is a premium 300 ml fuel additive designed to protect your diesel engine from water contamination and corrosion. It disperses water in the fuel tank for easy removal, prevents harmful fuel-water emulsions, and keeps your high-pressure fuel system clean and lubricated. This ash-free formula improves pump lubrication to cut wear, reduces deposits on injectors and lines, and safeguards against rust even in contaminated fuel.

Perfect for all diesel engines including those with turbochargers, catalytic converters, DPF filters, HVO, and XTL diesel. One 300 ml can treats up to 60 liters of fuel. Add every 2,000 km (1,200 miles) for ongoing protection and peak performance. Shelf life is 4 years when stored in a cool, dry place between 0°C and 30°C.

When to Use / Replace?

Use LIQUI MOLY 21649 when you suspect water in your fuel from condensation, bad pumps, or storage tanks - common in winter or after long sits. Ideal for vehicles driven in humid areas or with low-sulfur diesel. Replace or add fresh treatment every 2,000 km or monthly to maintain clean injectors, better combustion, smoother starts, and lower emissions. Regular use extends fuel system life, boosts fuel economy, and prevents breakdowns from corrosion or gumming.

• Cleans deposits for reliable power
• Lubricates pumps to reduce wear
• Protects in temps from -20°C to 50°C
• Saves money on repairs and fuel

FAQ

Is LIQUI MOLY 21649 safe for my DPF filter? Yes, it's fully compatible with DPF, catalytic converters, and all modern diesel systems - no ash buildup.

How much fuel does one bottle treat? 300 ml handles up to 60 liters, perfect for a full tank.

Can I use it preventively? Absolutely, add every 2,000 km to keep water out and engine running strong year-round.