Diesel engines are well-known for their longevity and reliability. However, most diesel-engine drivers know that their robust engines can be sensitive to carbon buildup, water contamination, improper combustion and gelling in winter. This often results in difficult starting, excessive exhaust smoke and lack of power, not to mention premature engine wear.
What makes things worse, is that in the last few decades, diesel fuel has been made leaner and cleaner to decrease pollution. The flipside is that this ULSD (Ultra Low Sulphur Diesel) lubricates your engine less than the diesel fuel of yesteryear.
That’s why, if you want your engine to last longer and perform better, you should add a diesel additive to your fuel with each fuel stop. A good diesel fuel additive adds lubricity, enhances power output, removes water contamination, removes carbon buildup, cleans the fuel injectors and prevents icing and diesel-filter clogging in winter.
In most cases where there are no major mechanical issues, a quality additive will greatly improve combustion and performance, even with very high mileage vehicles. Diesel fuel additives also contribute to greater longevity and lower maintenance costs.
We (re)searched the automotive market for the best diesel fuel additives and selected the two best you can buy: one that is formulated for sub-freezing temperatures and one that performs best in summer. For those who want the most bang for their buck, we found a great budget diesel additive too, which you can use year-round.
Check out the diesel fuel additives we recommend:
Best for Winter
Best for Summer
How we did our review
Over the years we’ve tried different additives to improve our old, high mileage diesel engine’s performance and make it smoke less. Because we live in a climate with below-freezing temperatures, we use winter diesel additives to keep the diesel fuel from gelling too.
Most products that promised a miraculous rebuild-in-a-bottle made no noticeable difference, while a few yielded pretty amazing improvement. Just goes to show that between all that snake oil, there are products that really make a difference. In our experience, those good ones enhance performance, improve combustion, remove excessive soot, clean injectors and remove water from your fuel system. That’s a win in our book!
With all that experience in our rucksack as a reference, we went out on a long journey and dove deep in all the manufacturer specifications. We listened to what diesel experts have to say and looked at tons of customer reviews to see what the customers’ experiences are.
The diesel fuel additives we recommend did an excellent job for us and the vast majority of other car enthusiasts, as well as for the diesel experts. We’ve selected 3 different additives to choose from: for winter, for summer and a budget-friendly year-round option. This will make it easy for you to choose the right diesel fuel additive for your vehicle, depending on when or what you intend to use it for.
Hot Shot’s Secret Diesel Winter additive is our recommended winter diesel additive. Regardless of the quality or grade of diesel fuel your tank is filled with, this premium winter additive boosts your fuel’s cetane level, improves your engine’s performance and lubricates it, making it less smoky.
Most importantly, it also protects against gelling, even in extreme low winter temperatures. It lowers diesel fuel’s pour point to -65 °F and prevents fuel line freeze-ups down to -40 °F. This greatly improves cold weather operability and protects against freeze-ups and clogged fuel filters. It also contains a military-grade water dispersant that removes water from your diesel fuel.
With this winter diesel additive that is formulated for all kinds of diesel engines, you can start and operate your diesel engine with confidence, regardless how low temperatures drop.
Customers say that this additive works equally great for modern diesel engines as well as old pickups or farm equipment. They advise you to buy gallon jugs to refill this handy squeeze bottle, because this is much more affordable.
Hot Shot’s Secret Everyday Diesel Treatment, the hugely popular brand’s summer variant, is our preferred summer diesel additive. It boosts the performance of your diesel engine by increasing your fuel’s cetane by up to 7 points.
It also improves your DPF’s efficiency, cleans your injectors, adds lubrication, neutralizes acids and keeps rust and corrosion at bay by dispersing the water in your fuel. This makes your engine perform better, which translates into better fuel efficiency with less black smoke. Stabilizers keep your fuel in good shape too, even if it sits for longer periods of time.
Just like its winter variant, Hot Shot’s EDT is suitable for all kinds of diesel engines, brand-new or high mileage old-school ones.
Customers say that this arguably is the best diesel additive on the market. One guy said that his Cummins-engined truck and his backhoe start easier, run smoother and perform noticeably better. Another user stated that his truck’s tailpipe is actually cleaner than with the previous fuel treatment he had been using.
Don’t forget to check out the much more affordable one gallon bottle to refill your squeeze bottle, it can save you a lot of money.
Howes Diesel Treat has arguably been the most trusted diesel fuel additive for over one hundred years for professional equipment operators, farmers, truckers and consumers. It provides reliable lubrication year-round, prevents carbon deposits, removes water from diesel fuel and prevents it from gelling in winter. When you compare this additive to other high quality competitors, you’ll find it’s the most bang for your buck too.
Extra lubricity is needed to protect diesel engines against today’s Ultra Low Sulfur Diesel (ULSD) fuels. By providing added lubricity to injectors, pumps, and upper cylinders, it improves the performance and extends the life of all types of diesel engines.
Diesel Treat also contains a specialized detergent package to help prevent fuel injector deposits. Carbon deposits on diesel injector systems can cause issues like loss of engine power and premature wear. By preventing these deposits, Diesel Treat saves you money by improving performance and fuel economy.
Petroleum-based Diesel Treat demulsifies water, by safely pushing it out of the fuel using no alcohol or harmful solvents. This is very important, because water is abrasive to your fuel system and can lead to fuel filter icing, corrosion and pitting.
Last but not least, Howes Diesel Treat prevents fuel from gelling. Its special formula has been tested and proven time and again to prevent gelling in even the coldest weather. Owners of all types of diesel vehicles and equipment rely on the Howes family’s guaranteed product to keep them going all winter long.
A happy customer says that he added this stuff to the diesel fuel of his model 3120 John Deere tractor with a three cylinder Yanmar diesel engine. He says that the tractor now goes twice as fast on the same terrain in the same gear and that the engine no longer smokes when starting in cold weather down to minus 15 F.
Another customer states that he has been using this additive for many years for his ‘96 F250 7.3L with 390k. He just came back from a 1300 mile roundtrip, averaging 21 mpg including driving through the Blue Ridge Mountains. He says he also uses it in his diesel tractor.
Beware: At the time of this writing, a 2- or 6-pack is much more expensive than buying 1 bottle at a time. The math just ain’t mathin’… But nonetheless, a single 64 fl.oz. bottle that treats up to 320 gallons is a steal, any which way you look at it!
Comparison Table of the Best Diesel Fuel Additives
First of all, it’s important to use the right additive for the season: it’s best to use a winter diesel additive when below-freezing temperatures are forecasted, and a summer additive when there’s no chance temperatures will drop that low.
That’s because they both have their specific merits: A winter additive’s emphasis is on protecting your diesel fuel from gelling for better cold-weather starting in the harshest winter weather. A summer additive on the other hand, will make your diesel engine run smoother and last longer while boosting performance with less smoke.
Both additives also play a crucial role in making your diesel fuel safe to use under all circumstances by removing water in order to prevent internal fuel system corrosion.
All three diesel fuel additives are great choices and won’t disappoint. Our advice: If you don’t mind spending a bit more to get the very best, you want to go for our “Best Winter”- or “Best Summer”- diesel additive.
If you’re looking for the most bang for your buck, our “Best Budget” will protect and improve your diesel engine year-round for a lot less.
How Often Should You Add a Diesel Fuel additive?
You should add a diesel fuel additive with each fuel stop to get the best performance and the most longevity out of your diesel engine.
When to Add Diesel Fuel Additive?
It is highly recommended to add a quality diesel fuel additive with each fuel stop, year-round. A good diesel fuel additive adds lubricity, enhances power output, removes water contamination, removes carbon buildup, cleans the fuel injectors and prevents icing and diesel-filter clogging in winter. This boosts your diesel engine’s performance and makes it last longer with less maintenance costs.
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