Is your diesel engine hard to start, noisier, or blowing more smoke than it used to? The problem might not be mechanical - it could be your fuel. Many diesel owners are unaware that standard pump diesel often has a low cetane number, which delays ignition and undermines performance.

Over time, this leads to rough running and costly engine wear. Fortunately, there’s an easy fix.

What Is a Cetane Number?

The cetane number (CN) measures how quickly diesel fuel ignites under compression. Unlike gasoline, where higher octane resists ignition, diesel works best with higher cetane—fuel that ignites faster and burns more smoothly.

• High cetane = quick ignition and smooth, efficient combustion.
• Low cetane = delayed ignition, leading to a rough burn, knocking, and smoke.

In a diesel engine, even a slight ignition delay can create poor combustion and a cascade of problems.

The Cetane Gap: What’s Legally Allowed vs. What Engines Need

Here’s the problem: in most U.S. states, diesel fuel is only required to meet a minimum cetane rating of 40. But modern diesel engines are engineered to run best on fuel rated between 48 and 50. That means most pump diesel falls far below the level your engine actually needs for optimal performance.

This cetane shortfall explains why so many diesel owners experience rough starts, noisy idle, and black smoke even when their engines are well-maintained. The fuel simply doesn’t ignite as quickly or cleanly as it should, because it's not formulated to match modern engine design.

Without intervention, you’re likely running your engine on sub-optimal fuel day after day.

Six Ways Low Cetane Can Ruin Your Diesel

Running on low-cetane diesel disrupts engine timing and combustion quality. Here’s what you’ll notice:

1. Hard cold starts & white smoke: Fuel doesn’t ignite quickly in cold cylinders, causing longer cranking and smoke until the engine warms.
2. Knocking & rough idle: Delayed ignition causes pressure to spike suddenly, creating the harsh “diesel knock” and vibrations.
3. Black smoke & emissions: Incomplete combustion leads to soot and carbon - visible as black exhaust smoke.
4. Carbon buildup: Unburned fuel coats injectors, valves, pistons, turbos, and DPFs with carbon, leading to clogs and higher maintenance needs.
5. Reduced power & fuel economy: Late combustion wastes energy. You burn more fuel, get less push on the piston, and lose MPG.
6. Increased wear: Harsh combustion and excess soot stress internal engine parts, accelerating wear and oil contamination.

In short, low cetane makes your diesel louder, dirtier, and less efficient - harming performance and longevity.

Why Raising Cetane Helps

Boosting the cetane number realigns combustion timing, delivering faster ignition and more complete burns. Here’s the payoff:

• Smoother operation: Ignition happens on time, reducing knock and vibration. Your engine runs quieter and cleaner.
• Cleaner combustion: With less delay, fuel burns fully - cutting soot, smoke, and carbon buildup.
• Better cold starts: High cetane fuel ignites reliably, even in low temperatures, reducing startup smoke and hesitation.
• Improved MPG and power: Timely combustion uses fuel more efficiently, restoring throttle response and fuel economy.
• Lower emissions & wear: Cleaner combustion reduces unburned hydrocarbons, carbon monoxide, and soot blow-by - protecting after-treatment systems and internal engine components.

Raising cetane restores the smooth, efficient combustion your diesel was built for and it shows in both performance and long-term durability.

The Simple Solution: AR6500 Diesel Treatment

You don’t have to search for premium diesel to get high cetane. A quality additive can raise your fuel’s cetane number at every fill-up.

Archoil AR6500 Diesel Treatment is a powerful, all-in-one additive that boosts cetane by up to 8 points - bringing typical fuel into the optimal range for modern diesel engines. It improves ignition timing, reduces soot, and restores clean, complete combustion.

But AR6500 does more than just raise cetane:

• Advanced detergents keep injectors clean and prevent carbon deposits.
• Lubricity agents protect the fuel system and reduce wear.
• Fewer DPF regens and cleaner exhaust systems reduce downtime and repairs.

With every dose, AR6500 enhances combustion and protects your engine, helping it run stronger, cleaner, and longer.

How to Use It

Using AR6500 is easy - just add the recommended amount to your tank at each fill-up. It starts working immediately, improving ignition and conditioning your fuel system.

Drivers report smoother starts, less smoke, quieter idling, and noticeable fuel savings. It’s a low-cost way to prevent the costly side effects of low-cetane fuel.

Take Control of Your Diesel’s Performance

Don’t let hidden fuel quality issues sabotage your engine. With AR6500, you control the cetane number and protect your engine from the inside out.

Whether you’re towing, hauling, or commuting, your diesel deserves fuel that performs. Boosting cetane transforms ordinary diesel into clean-burning, high-performance fuel, delivering better starts, less smoke, and longer engine life.

Boost your cetane. Boost your diesel’s life.