6 Best Diesel Fuel Additives for Improving MPG That Save Without Sacrifice

You’re a hundred miles from the next town, watching the fuel gauge dip a little faster than you’d like. Every RVer, vanlifer, and skoolie owner knows that feeling. Fuel is one of our biggest recurring costs, and squeezing every last mile out of a gallon isn’t just a preference—it’s a core part of a sustainable life on the road.

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Why Diesel Additives Boost Your Rig’s MPG

Think of a diesel additive as a multi-vitamin for your fuel. Modern Ultra-Low Sulfur Diesel (ULSD) is clean-burning, but the process that removes sulfur also strips out natural lubricants. This leaves critical components like your high-pressure fuel pump and injectors vulnerable to premature wear. An additive restores that essential lubricity, reducing friction and helping the entire system run more efficiently.

But it’s not just about lubrication. The best additives also boost the cetane number of your fuel. Cetane is to diesel what octane is to gasoline; a higher number means the fuel ignites faster and burns more completely. This complete combustion translates directly into more power from every drop of fuel, which means your engine doesn’t have to work as hard to maintain speed. The result is a quieter, smoother-running engine and, most importantly, better miles per gallon.

Finally, these formulas are powerful detergents. Over time, carbon deposits build up on your fuel injectors, disrupting the fine mist-like spray pattern needed for efficient combustion. Instead of a clean spray, you get drips and streams that waste fuel and reduce power. Additives dissolve these deposits, restoring injector performance to factory-spec. A clean fuel system is an efficient fuel system, period.

Hot Shot’s Secret EDT: All-Around Performer

If you’re just starting with additives, Hot Shot’s Secret Everyday Diesel Treatment (EDT) is a fantastic place to begin. It’s a true jack-of-all-trades that addresses the most common needs of a diesel engine in one bottle. It provides a significant cetane boost—typically 6 to 8 points—which you’ll feel as a smoother idle and better throttle response.

What makes EDT so practical for life on the road is its comprehensive formula. It adds lubricity to protect your fuel system, includes detergents to keep injectors clean, and contains a water demulsifier to separate water from your fuel, protecting your system from corrosion. It also stabilizes fuel for up to two years, a huge benefit if your rig sits for extended periods between trips. It’s the reliable, do-it-all option that delivers noticeable MPG gains without requiring you to play chemist.

Power Service Diesel Kleen for Cetane Boost

When you want a direct and noticeable impact on performance and MPG, Power Service Diesel Kleen + Cetane Boost is the classic choice. This stuff has been around forever for a reason: it works. Its primary function is to jack up your fuel’s cetane rating, and it does so exceptionally well. You’ll often see a 1-2 MPG improvement, especially if you’ve been filling up with lower-quality diesel.

This additive is for the driver who can feel the difference in their rig. If your engine feels sluggish climbing a grade or sounds a bit clattery, a dose of Diesel Kleen often smooths things right out. By ensuring a more complete burn, it not only improves fuel economy but also reduces exhaust emissions and engine wear. For pure, unadulterated combustion efficiency, it’s tough to beat. Just be sure to grab their white bottle (Diesel Fuel Supplement + Cetane Boost) for winter, as it includes an anti-gel.

Lucas Fuel Treatment for Consistent MPG Gains

Lucas Fuel Treatment is an old-school legend, and its reputation is built on consistency. It’s not about a dramatic, one-tank transformation. Instead, it’s designed for long-term engine health and steady, reliable MPG improvement. Its super-slick formula is focused heavily on lubrication, coating your entire fuel system to reduce wear and tear on injectors and pumps.

This is the perfect additive for older rigs or anyone who values longevity as much as immediate fuel savings. By cleaning and lubricating the upper cylinders, it ensures your engine operates with less friction, which naturally leads to better efficiency over time. While the cetane boost is milder than competitors, its ability to neutralize the harmful effects of low-sulfur fuel makes it a workhorse for preserving your engine for the long haul. Think of it less as a performance enhancer and more as a long-term investment in your rig’s powertrain.

Stanadyne Performance Formula: OEM Trusted

When engine manufacturers put their name behind an additive, you should pay attention. Stanadyne is unique because it’s developed by a fuel injection system manufacturer, and it’s the only additive recommended by major OEMs like Ford, GM, John Deere, and Navistar. That’s a powerful endorsement that speaks to its safety and effectiveness, especially for newer, more complex diesel engines still under warranty.

Stanadyne Performance Formula takes a balanced approach. It offers a solid 5-point cetane boost, excellent lubricity to protect sensitive high-pressure common rail (HPCR) systems, and strong detergents to prevent injector deposits. It’s also an all-season, all-in-one product, providing cold-weather protection against gelling. If you’re driving a newer truck or van and are wary of "miracle-in-a-bottle" claims, Stanadyne is the safest and most trusted bet on the market.

Opti-Lube XPD for Maximum Lubricity & MPG

For the owner who wants the absolute best protection for their fuel system, Opti-Lube XPD is the top contender. In independent testing, it consistently ranks at or near the top for lubricity. Why does this matter so much? Because your high-pressure fuel pump and injectors are incredibly expensive components, and ULSD fuel simply doesn’t protect them adequately. XPD creates a powerful protective film that dramatically reduces wear.

This superior lubrication has a direct effect on MPG. A system operating with less friction is inherently more efficient. Combine that with a 3 to 5-point cetane improver and powerful detergents, and you get an additive that delivers both best-in-class protection and fantastic fuel economy gains. It’s a premium product with a price to match, but for those running modern, high-pressure diesel engines, the cost is easily justified by the long-term savings in repairs and fuel.

Amsoil Diesel All-In-One for Engine Health

Amsoil approaches fuel additives from a total engine health perspective. Their Diesel All-In-One is arguably the most comprehensive formula available, bundling every conceivable benefit into a single, potent treatment. It delivers a substantial cetane boost, superior lubricity, and aggressive detergents that clean not only existing deposits but also prevent new ones from forming.

Where Amsoil really stands out is its holistic approach. The formula improves cold-flow properties to prevent gelling in the winter while also acting as a fuel stabilizer for long-term storage. It’s engineered to do everything well, making it the ideal choice for the RVer who travels through all seasons and climates. If you want to simplify your maintenance routine with one bottle that maximizes MPG, protects against wear, and prepares your rig for any weather, Amsoil is the premium, no-compromise solution.

Matching an Additive to Your Driving Style

There is no single "best" additive; there’s only the best one for your engine, your fuel quality, and your travel habits. The key is to match the product’s strengths to your needs. Don’t just grab the bottle with the biggest MPG claim. Think about how you use your rig.

Are you a full-timer constantly on the move, covering long highway miles?

• A cetane-focused additive like Power Service Diesel Kleen or a balanced performer like Hot Shot’s Secret EDT will deliver immediate and satisfying MPG returns.

Do you have an older rig with a mechanical injection system, or is long-term reliability your absolute top priority?

• The superior lubrication from Lucas Fuel Treatment or Opti-Lube XPD will be your best investment, preserving expensive parts while providing steady efficiency gains.

Are you driving a newer vehicle, especially one still under warranty, or do you travel through extreme hot and cold climates?

• An OEM-approved, all-season formula like Stanadyne Performance Formula or a comprehensive treatment like Amsoil All-In-One provides peace of mind and covers all your bases.

The right choice isn’t about chasing a magic number. It’s about understanding what your engine needs most. Start with one that aligns with your priorities, run a few full tanks with it, and track your mileage. The data won’t lie.

Ultimately, using a quality diesel additive is one of the cheapest and easiest forms of preventative maintenance you can perform. It’s a small, consistent investment that pays for itself in fuel savings while protecting your engine for the thousands of miles ahead. Choose wisely, and you’ll save without sacrificing a single mile of your adventure.