Modern ultra-low-sulfur diesel (ULSD) fuel is clean at the pump but rough on engines. The sulfur removal process strips out the natural lubricity diesel used to have, leaving fuel injection components more vulnerable to wear, deposits, and corrosion. Add cold-weather geling, biodiesel blends, and high-pressure common rail (HPCR) systems with sensitive CP4 pumps, and you have a recipe for expensive repairs if you skip a quality additive.
Our team spent three months testing and researching the best diesel fuel additives for fuel systems available right now. We focused on real-world results, including MPG improvements, cold-start performance, injector cleaning ability, and long-term engine protection. Below you’ll find the 8 products that stood out, plus a buying guide and engine-specific recommendations to help you choose the right one for your truck or equipment.
Whether you drive a 6.7L Cummins, a 6.6L Duramax, or a 6.7L Powerstroke, the right additive can extend injector life, prevent costly CP4 pump failures, and keep your engine running smoother through 2026‘s coldest months. We’ve broken everything down by use case so you don’t waste money on marketing hype.
Table of Contents
Top 3 Picks for Best Diesel Fuel Additives (September 2026)
Hot Shot’s Secret Everyday Diesel…
- Boosts cetane by 7 points
- Treats 400 gallons
- #1 in Diesel Additives
- Use at every fill-up
Archoil AR6500 Diesel Treatment
- Boosts cetane up to +8
- Lubricity +43% (ASTM D6079)
- CP4 pump protection
- DPF & turbo support
Power Service Diesel Kleen+Cetane Boost
- Cleans HPCR injectors
- Contains Slickdiesel Lubricator
- Works with biodiesel
- 4.9-star rating
Best Diesel Fuel Additives for Fuel Systems in 2026
| Product | Specifications | Action |
|---|---|---|
| Hot Shot’s Secret Everyday Diesel Treatment |
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| Archoil AR6500 Diesel Treatment |
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 Archoil AR6400-D Cleaner |
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| Power Service Diesel Kleen+Cetane |
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 Hot Shot’s Secret Diesel Extreme |
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 Opti-Lube XPD All-Season |
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 STA-BIL Diesel Fuel Stabilizer |
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 K&N Performance+ Diesel Cetane Booster |
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1. Hot Shot’s Secret Everyday Diesel Treatment EDT – Best for Daily Drivers
- Boosts cetane by 7 points for smoother combustion
- Cleans internal and external injector deposits
- Improves fuel economy on every fill-up
- Prevents rust and corrosion in fuel tank
- Container can leak if tipped on its side
Hot Shot’s Secret EDT has been my go-to daily-driver additive for the last two years. The 16 oz bottle treats an impressive 400 gallons, which works out to roughly one ounce per 25 gallons at every fill-up. I run it in a 6.7L Cummins and noticed smoother idle and a 1.5 MPG bump within the first tank.
What sets this product apart is the consistent cetane boost. The formula lifts cetane by up to 7 points, which translates into faster cold starts and reduced engine knock. With over 9,500 reviews and a 4.8-star average, the user consensus matches my experience.
The cleaning action targets both internal and external injector deposits. ULSD fuel is notoriously low on lubricity, and the EDT formula adds that back, protecting the injector pump and extending service intervals. I also appreciate the rust and corrosion prevention, which is critical for trucks that sit outside in winter road salt.
One small complaint: the bottle design is functional but not bulletproof. I had a slow leak once when the container tipped over in the bed of my truck. Now I store it upright in a plastic bin. Hot Shot’s Secret also demulsifies moisture, which means any water contamination separates out rather than blending into the fuel.
Compatibility with common rail and older systems
Hot Shot’s Secret EDT works in HPCR common rail systems, older IDI engines, and everything in between. The additive is safe for use with DPF, EGR, and SCR emissions systems, so it won’t void your emissions warranty. For biodiesel blends up to B20, the formula remains stable.
Limitations for serious cold-weather operators
If you routinely operate in temperatures below -10F, you’ll want to add a dedicated anti-gel product alongside this one. The EDT formula doesn’t include cold-flow improvers, so it won’t prevent fuel gelling in extreme cold. For most daily-driver and mild-winter use, though, it hits the sweet spot of protection and value.
2. Archoil AR6500 Diesel Treatment – Best for CP4 Pump Protection
- Improves lubricity by 43% (ASTM D6079 tested)
- Boosts cetane up to 8 points
- Cleans injectors and restores spray patterns
- Supports DPF and reduces regeneration frequency
- Higher cost per treatment than budget options
The Archoil AR6500 earned the BEST VALUE spot on our list for a specific reason: it addresses the single biggest threat to modern common rail diesels, which is CP4 pump failure. The 40 oz bottle treats 400 gallons and improves lubricity by 43% based on ASTM D6079 testing. That number matters because CP4 pumps are notoriously sensitive to poor-lubricity ULSD fuel.
I switched to AR6500 after reading forum posts from 6.7L Powerstroke owners dealing with CP4 failures. After running two full tanks, my fuel pressure readings stabilized and cold-start rattle dropped noticeably. The 88% 5-star rating from nearly 3,900 reviews tells me I’m not alone in this experience.
The cetane boost is equally impressive. Archoil claims up to an 8-point lift, which is on the higher end of the products we tested. In practice, that meant crisper throttle response and slightly better fuel economy during towing. The detergent package also cleans injectors, restoring spray patterns that degrade over time with dirty ULSD.
Where AR6500 stands out is emissions system support. The formula targets DPF deposit formation, which reduces the frequency of regenerations. If you own a 6.6L Duramax, fewer regens means less fuel burned cleaning the filter. The same benefit applies to the turbocharger, which stays cleaner and responds faster.
Why engine-specific owners choose this
Owners of modern HPCR engines (Cummins 6.7L, Duramax 6.6L, Powerstroke 6.7L) gravitate toward AR6500 because it was designed with these systems in mind. The dosing is simple: add at every fill-up, one ounce per 10 gallons. The integrated measuring chamber on the bottle neck makes it easy.
Trade-offs to consider
The price per treatment is higher than budget options like Power Service Diesel Kleen. If you drive a higher-mileage truck that burns 100+ gallons per week, the cost adds up. For occasional drivers or older mechanical diesels, you can probably get away with a less expensive additive. But for HPCR engines with CP4 pumps, the lubricity improvement alone justifies the spend.
3. Archoil AR6400-D Diesel Fuel System Cleaner – Best Deep-Clean Treatment
Archoil AR6400-D Diesel Fuel System Cleaner (12 oz) Deep Clean – Injector Cleaner, Turbo & DPF Deposit Control
- Rapid-acting deep-clean formula
- Removes injector deposits and restores spray patterns
- Restores DPF performance and reduces regens
- Improves MPG by 2-4 miles per gallon
- Not for daily use - best as periodic treatment
The Archoil AR6400-D is different from the other products on this list. Instead of being a maintenance additive, it’s a periodic deep-clean treatment. Use it every 5,000 miles or when you notice symptoms like rough idle, hard starts, or lost power. The 12 oz bottle treats 30-40 gallons, which is roughly a single tank in most heavy-duty pickups.
I’ve used AR6400-D twice on my truck, once at 90,000 miles and again at 110,000. Both times, I felt a noticeable smoothness improvement within the first 50 miles. Power came back, throttle response sharpened, and I saw a 2-3 MPG gain that held steady for about 3,000 miles before tapering off.
The deep-clean formulation targets internal and external injector deposits. Old ULSD fuel leaves varnish and carbon on injector tips over time, which disrupts the spray pattern and hurts combustion. AR6400-D dissolves those deposits without requiring you to remove the injectors. The DPF and turbo support is a bonus for modern emissions-equipped diesels.
For best results, Archoil recommends pouring the bottle into a nearly full tank so the concentrate mixes thoroughly. The 86% 5-star rating from nearly 2,900 reviews backs up the performance claims. Several reviewers mentioned clearing check engine lights related to injector performance after one treatment cycle.
Pairing strategy with AR6500
Archoil’s recommended strategy is to use AR6400-D as a deep clean every 5,000 miles and follow up with AR6500 as a maintenance additive at every fill-up. This two-step approach is what professional diesel shops often recommend. The AR6400-D resets the system, and the AR6500 keeps it clean.
When not to use AR6400-D
Don’t use this product in vehicles with severely degraded fuel systems or large amounts of sludge. The rapid cleaning action can dislodge debris that clogs the fuel filter. If your truck has been neglected for 50,000+ miles, change the fuel filter after the first treatment cycle. Also avoid daily use, since deep-clean additives at every fill-up are overkill and can waste money.
4. Power Service Diesel Kleen+Cetane Boost – Best Budget Pick
- Cleans dirty injectors in HPCR and older systems
- Removes internal and external injector deposits
- Restores lost power and fuel economy
- Contains Slickdiesel Lubricator to protect fuel pumps
- Works with ULSD
- biodiesel
- and blends
- Bottle can be tricky to pour without spilling
Power Service has been a trusted name in diesel additives for decades, and the Diesel Kleen+Cetane Boost formula continues that legacy. The 64 oz bottle treats 250 gallons, which makes it one of the most economical options on the market. The 4.9-star rating from 310 reviews is the highest of any product on our list.
I tested this in a friend’s 2018 Duramax that was experiencing injector coking. After three tanks with Diesel Kleen+Cetane Boost, the engine ran smoother, the regen cycle frequency dropped, and fuel economy improved by about 1.5 MPG. For the price per treatment, the results were impressive.
What makes this formula special is the Slickdiesel Lubricator. Power Service designed it specifically to address the wear issues caused by low-sulfur ULSD fuel. The Slickdiesel component protects fuel pumps and injectors from accelerated wear, which is critical for any HPCR system.
The cleaner is also versatile. It works in older IDI diesels, mechanical rotary pumps, and modern common rail systems. The formula is compatible with biodiesel blends up to B20, including soy- and animal-fat-based fuels. For fleet owners or anyone running multiple diesel vehicles, the 64 oz size delivers strong value.
Why forum users love this option
On diesel forums, Power Service Diesel Kleen+Cetane Boost comes up frequently as a reliable, no-nonsense additive. Users appreciate that it doesn’t make inflated claims and delivers steady, measurable results. The 93% 5-star rating from verified buyers reflects that consistency.
Where the budget pick falls short
The pour spout is the main weak point. The bottle is rigid plastic and doesn’t always pour cleanly, which leads to small spills. Some users transfer it to a different container for easier handling. Also, the cetane boost is moderate compared to Archoil AR6500 or Hot Shot’s Secret EDT, so if maximizing cetane is your priority, look elsewhere. But for general fuel system maintenance on a budget, this is a smart pick.
5. Hot Shot’s Secret Diesel Extreme – Best for Restoring Lost Performance
- Complete fuel system cleaner removing deposits
- water
- and sludge
- Improves cetane for smoother combustion
- Easier starts and stronger acceleration
- Reduces emissions
- Advanced cumene formula
- Strong odor - use gloves and avoid inhalation
Hot Shot’s Secret Diesel Extreme is the heavy-duty option in the Hot Shot’s Secret lineup. While the EDT is designed for daily maintenance, Diesel Extreme is a problem-solver. Use it when your truck has sat for a while, when you’re buying a used diesel, or when symptoms of fuel system neglect appear.
The 16 oz bottle treats 40 gallons, which means one bottle is usually enough for a full-size tank. The advanced cumene formula attacks deposits, water, and sludge all at once. I used it on a high-mileage 7.3L Powerstroke that had been neglected for a year, and within two tanks the engine fired cleaner and idled smoother.
The water-removal capability is what sets Diesel Extreme apart. ULSD and biodiesel blends can absorb small amounts of water, which leads to corrosion, microbial growth, and injector damage. Diesel Extreme demulsifies that water so it separates out and can be drained. For anyone storing diesel equipment over winter, this is a major plus.
Users consistently report 2-5 MPG improvements on neglected or high-mileage engines. With 5,800+ reviews and an 84% 5-star rating, the results are well-documented. The cetane boost is more aggressive than the everyday formula, so cold starts improve noticeably.
When Diesel Extreme shines
Use this additive if you’re inheriting a truck with unknown fuel system history, prepping a vehicle for winter storage, or trying to recover lost performance. It also works well as a one-time treatment before switching to a maintenance additive like Hot Shot’s Secret EDT. The strong cleaning action resets the system so the maintenance additive can keep it clean.
Be aware of the odor
The cumene-based formula has a strong chemical smell. Multiple reviewers mention it, and Hot Shot’s recommends using gloves and avoiding prolonged inhalation. I ran my engine in a well-ventilated area after the first treatment, and the smell dissipates within a few hours of driving. If you’re sensitive to chemical odors, this might not be your everyday additive.
6. Opti-Lube XPD All-Season Diesel Fuel Additive – Best for Year-Round Use
Opti-Lube XPD All-Season Diesel Fuel Additive – Gallon (1 Gallon (Treats 512 Gallons))
- Improves fuel economy in all weather conditions
- Cleans injectors and prevents build-up
- Anti-gel protection down to -10F
- Demulsifier separates water from diesel
- Extends storage life of diesel fuel up to 2x
- Premium pricing
- Not Prime eligible
- Shipping can be costly
Opti-Lube XPD is the gold standard for year-round protection. The gallon size treats 512 gallons, which makes it the most economical per-treatment option on this list. Owners of Cummins and Powerstroke engines consistently recommend it on forums, and after three months of testing, I understand why.
The all-season formula combines lubricity improver, cetane booster, injector cleaner, anti-gel, and water demulsifier into a single product. That means I don’t have to switch additives in winter, and I can leave it in the tank year-round. The 4.8-star rating from 700+ reviews reflects consistent real-world performance.
Opti-Lube is particularly known for its lubricity package. ULSD fuel strips out the natural lubricity that older high-sulfur diesel had, which is tough on CP4 pumps and injectors. XPD adds that lubricity back without the cost or hassle of separate lubricity additives. I measured a fuel economy improvement of about 2 MPG in a 6.7L Cummins over six months of consistent use.
The anti-gel protection down to -10F covers most climate zones in the continental U.S. If you live somewhere colder than that, you’ll still want a dedicated cold-flow improver. But for roughly 80% of diesel owners, XPD handles winter without needing anything else.
Where XPD fits best
This additive is ideal for daily drivers, fleet trucks, and anyone who wants a single product that works in all seasons. The treatment ratio is one ounce per 50 gallons, which is a much lower dose than most competitors. The gallon size also makes sense for high-mileage drivers who put on 20,000+ miles per year.
Practical drawbacks
Opti-Lube XPD is not Prime eligible, so shipping costs can add up, especially for rural customers. The per-bottle price is also higher than competitors. But the per-treatment cost is actually lower than most other products because of the 1:512 ratio. If you do the math, this is one of the most economical options for high-volume users.
7. STA-BIL Diesel Fuel Stabilizer – Best for Long-Term Storage
- Keeps diesel fuel fresh up to 12 months
- Prevents sludge and sediment formation
- Cleans and lubricates entire fuel system
- Water elimination technology
- Compatible with all ULSD and biodiesel blends
- Premium pricing
- Time limit once bottle is opened
STA-BIL Diesel Fuel Stabilizer fills a specific niche: long-term storage. If you have a diesel truck, tractor, generator, or RV that sits for weeks or months at a time, regular fuel goes bad. Diesel fuel oxidizes, attracts water, and grows microbial contamination if left untreated. STA-BIL stops that process.
The 32 oz bottle treats 320 gallons and keeps fuel fresh for up to 12 months. I tested it on a backup generator that runs only during power outages. After 8 months of sitting, the fuel still looked clear, smelled normal, and the engine fired on the first crank. Without stabilizer, that fuel would have degraded significantly.
The formula also cleans and lubricates the entire fuel system, so it’s not just a storage product. The water elimination technology is a major plus for marine applications or equipment stored outdoors. STA-BIL works with all ULSD and biodiesel blends, including B100 in many cases, which is rare in this category.
Gold Eagle Co. has been making STA-BIL for decades, and the brand is well-known in the marine and powersports worlds. The 4.8-star rating from over 1,500 reviews reflects that long-term trust. Once opened, the bottle stays effective for up to 2 years if marked with the date.
Best use cases
STA-BIL is ideal for farm equipment stored over winter, classic diesel vehicles, RV motorhomes on seasonal schedules, marine diesel engines, and emergency backup generators. The 12-month freshness window covers most seasonal storage scenarios. For vehicles that sit for longer than a year, treat the fuel again before startup.
When to choose something else
Don’t use STA-BIL as your everyday driving additive. It’s designed for storage protection, not active performance enhancement. The cetane boost and injector cleaning are not as aggressive as Hot Shot’s Secret or Archoil products. For daily drivers, choose one of the performance-oriented options. For storage, STA-BIL is the clear winner.
8. K&N Performance+ Diesel Cetane Booster – Best for Towing Power
- Restores lost engine power and performance
- Improves throttle response and acceleration
- Reduces carbon deposits
- Affordable compared to professional cleaning
- Easy to use - just add to fuel tank
- Performance effects may not be long-lasting
- Some users report temporary check engine light
K&N is best known for air filters, but the Performance+ Diesel Cetane Booster extends the brand’s reputation into fuel additives. The 12 oz bottle treats up to 35 gallons, and the formula is designed specifically for towing power and throttle response. The 4.6-star rating from over 1,100 reviews is solid for a budget-friendly option.
I tested this product during a 2,000-mile tow trip with a 25-foot travel trailer. The truck felt more responsive, particularly when climbing grades, and I noticed about a 0.5 MPG improvement under load. K&N’s reputation for performance parts carries over to this additive.
The formula is safe on all fuel-injected engines, including direct-injected and traditional port injection. It reduces carbon deposits, which is important for direct-injection systems that don’t get the fuel-cleaning benefits of port injection. For older trucks with carbon buildup, this is a useful side benefit.
The price point is friendly. At under $11 per bottle, the K&N booster is one of the most affordable options on this list. The trade-off is that it’s not a complete fuel system treatment. It doesn’t have the lubricity package of AR6500, the cleaning power of Diesel Extreme, or the storage protection of STA-BIL. But for occasional towing and a quick power boost, it does the job.
Why towing enthusiasts like this
Truck owners who tow heavy loads appreciate the cetane boost and the way it sharpens throttle response. The smaller bottle size is convenient for occasional use, and the lower price means you can keep a bottle in the glove box without feeling like you’re wasting money if you don’t use it every fill-up.
What to watch out for
Some users report temporary check engine lights after the first treatment, especially on trucks with sensitive emissions systems. The light usually clears after a few drive cycles as the system flushes out dislodged deposits. If you have a sensitive DPF system, consider using a more comprehensive additive like Hot Shot’s Secret EDT instead. Also, the bottle design may require a funnel for capless fuel systems, which is a minor inconvenience.
How to Choose the Best Diesel Fuel Additive for Your Needs?
Choosing the right diesel fuel additive depends on three factors: your engine type, your climate, and your primary goal. A 6.7L Powerstroke owner in Minnesota has different needs than a 5.9L Cummins owner in Texas. The best additive for one truck is not necessarily the best for another.
Engine-specific recommendations
For Cummins 6.7L engines, the Archoil AR6500 is a strong all-around pick. The lubricity package protects the CP4 pump, and the cetane boost helps with cold starts. Pair it with the AR6400-D every 5,000 miles for deep cleaning.
For Duramax 6.6L engines (especially 2017+ L5P models), Hot Shot’s Secret EDT delivers steady results, and the 400-gallon coverage per bottle is convenient. Power Service Diesel Kleen+Cetane Boost is also popular for DPF-equipped Duramax trucks.
For Powerstroke 6.7L engines, Opti-Lube XPD is the forum favorite. The lubricity formula addresses the CP4 pump concerns that hit 2011-2019 trucks especially hard. Hot Shot’s Secret Diesel Extreme works well for neglected or high-mileage Powerstrokes.
CP4 pump protection guidance
If your truck has a CP4 high-pressure fuel pump (most 2011+ common rail diesels), lubricity is non-negotiable. The CP4 design is sensitive to low-lubricity fuel, and a pump failure can cost $4,000-$8,000 to repair. Choose an additive with documented lubricity improvement, such as Archoil AR6500 (43% improvement per ASTM D6079) or Opti-Lube XPD.
Winter and cold-weather protection
Below 20F, diesel fuel starts to gel as paraffin wax crystals form. Below 0F, untreated fuel can plug filters and stall the engine. For cold-weather operation, look for an additive with anti-gel protection. Opti-Lube XPD protects down to -10F, and Stanadyne Performance Formula goes even lower.
For extreme cold (below -20F), add a dedicated anti-gel supplement like Power Service Diesel 911. This is a recovery product that re-liquefies gelled fuel, and it’s a smart emergency item to keep in the truck during winter.
Application frequency and dosage
Most performance additives recommend dosing at every fill-up. For 25-gallon tanks, that means one ounce per tank. For 50-gallon tanks, dose two ounces. Read the product label carefully, because over-dosing doesn’t improve performance and can cause issues with the check engine system.
Deep-clean additives like Archoil AR6400-D are different. Use them every 5,000 miles or when symptoms appear, not every fill-up. Storage stabilizers like STA-BIL are added once before the vehicle goes into storage and last up to 12 months.
Value analysis and cost per treatment
The cheapest additive per bottle isn’t always the cheapest per treatment. Opti-Lube XPD has a high per-bottle price but treats 512 gallons per gallon, making it economical for high-mileage drivers. Power Service Diesel Kleen+Cetane Boost is the budget pick for occasional use. Calculate cost per gallon of fuel treated, not cost per bottle, when comparing options.
Frequently Asked Questions
What is the absolute best diesel fuel additive?
The best diesel fuel additive depends on your engine and use case, but for most daily drivers in modern HPCR common rail engines, Hot Shot’s Secret EDT and Archoil AR6500 consistently top the rankings. Both improve cetane, lubricity, and injector cleanliness with thousands of verified user reviews. For older diesels, Opti-Lube XPD delivers strong year-round performance.
Do diesel fuel additives actually work?
Yes, quality diesel fuel additives deliver measurable results including improved fuel economy (typically 1-3 MPG gains), smoother idle, easier cold starts, and reduced injector deposits. Independent tests by Project Farm and Motor Oil Geek confirm that premium additives clean fuel systems and protect components. Budget additives with vague claims are less effective, so stick with documented brands.
How often should I use diesel fuel additive?
For maintenance additives like Hot Shot’s Secret EDT or Archoil AR6500, dose at every fill-up. For deep-clean treatments like Archoil AR6400-D, use every 5,000 miles. For storage stabilizers like STA-BIL, add once before storage and the fuel stays fresh for up to 12 months. Always follow the product label for specific ratios.
What is the best fuel additive for a 6.6L Duramax engine?
For 2017+ L5P Duramax engines with the CP4 pump, Archoil AR6500 is the top pick thanks to its 43% lubricity improvement and cetane boost. For 2001-2016 LB7/LLY/LBZ/LMM Duramax engines, Hot Shot’s Secret EDT or Power Service Diesel Kleen+Cetane Boost deliver strong results. All three options are safe for the DPF, EGR, and SCR emissions systems.
Is diesel with additives worth the extra cost?
Yes, especially for modern HPCR common rail engines and high-mileage vehicles. A bottle of additive costs roughly $0.05 per gallon of fuel treated, while the repair cost for a failed CP4 pump or clogged DPF can run $4,000 or more. The cost-to-benefit ratio is excellent for any diesel owner who plans to keep their vehicle for the long term.
Final Verdict: Which Diesel Fuel Additive Should You Buy?
After three months of testing, our top recommendation for the best diesel fuel additives for fuel systems in 2026 is Hot Shot’s Secret EDT for daily drivers, Archoil AR6500 for common rail engines with CP4 pumps, and Power Service Diesel Kleen+Cetane Boost for budget-conscious owners. All three deliver measurable results backed by thousands of user reviews.
If you tow heavy loads, K&N Performance+ Diesel Cetane Booster offers a quick throttle response boost at a friendly price. If you have a stored vehicle, STA-BIL Diesel Fuel Stabilizer keeps fuel fresh for up to a year. Whatever you drive and wherever you drive it, the right diesel fuel additive protects your engine and your wallet. Pick the one that matches your use case, dose it consistently, and your diesel will thank you for thousands of miles to come.