What Is Cetane and Why Does It Matter?

 

Cetane is a colorless, liquid hydrocarbon of the alkanediesel_photo series, C 16 34, used as a solvent and in cetane number determinations. In the same way that octane number ratings are applied to rate the ignition stability of gasoline, cetane values are assigned to diesel fuel to rate its combustion quality. Cetane numbers are used to indicate the combustion speed of diesel fuel. Diesel fuels with higher cetane ratings have shorter ignition delays, providing more complete combustion and allowing engines to operate more effectively.

We asked mechanical engineer Mark Nyholm, AMSOIL Product Manager – Heavy Duty, to elaborate on the importance of understanding cetane and why AMSOIL carries Diesel Cetane Boost in its diesel products line.

If diesel engines operate better with higher cetane values, why is most diesel fuel only between 40 and 45?

Mark Nyholm: This is a really great question and I believe it comes down to economics from the perspective of the fuel refinery. If the crude oil they have will provide a cetane value of, let’s say, 40 and today’s engines run at optimum efficiency with a cetane value of 48, what incentive does the refinery have to improve the cetane value? Will the market bear the increase per gallon of diesel if the refinery adds cetane improver? The answers really are “none,” and “not really.” Most diesel owners don’t have a clue what cetane does for them let alone what is the appropriate number they should have for their engine. Since cetane value is not published at the pump, all diesel owners know is to pull the green-handled ULSD pump and fill up the tank. The limit was set so that all fuels could reasonably achieve this minimum 40 number without adding a bunch of cetane improver to it. That value I also imagine was determined by the EMA to be “acceptable” for operation, even though not ideal.

Who is this product designed for? OTR truckers primarily or hardcore diesel-truck enthusiasts?

MN: Typically enthusiasts will buy cetane improvers. Now, you will find enthusiasts in about every market out there, so it’s hard to narrow down which market buys the most in volume. If I were to guess, I’d say the two most popular applications that use cetane improvers are turbodiesel pickups and class 8 OTR trucks.

How does increased cetane reduce smoke and emissions and improve fuel economy?

MN: Cetane number is a measure of combustion efficiency. The higher the number the better potential for each and every droplet that is sprayed into the combustion chamber to burn and produce power. The more efficient that fuel burns in the combustion chamber the less possibility to produce smoke and byproducts of combustion that the exhaust after treatment system must manage. The more of that fuel that burns the better power output and better possible fuel mileage you can expect to achieve from the engine.

To learn more or purchase AMSOIL Cetane Boost, visit our web page here.

Visit amsoil.com/diesel for more information on all our AMSOIL products for diesel owners.

automatic transmission issues

Do Transmission Fluid Additives Work? John Baker| Feb 26, 2024 9:04 AM Walk the aisles of most auto parts stores and you’ll find multiple “mechanic-in-a-bottle”-type additives that claim to restore transmission performance. The claims made typically include some variation of the following: • Frees stuck valves to improve shifting • Fixes transmission slipping • Restores smooth […]

Understanding Oil Viscosity Viscosity is the measure of a fluid’s resistance to flow. _by David Hilgendorf|January 17, 2023 The physical properties of lubricants are measured by characteristics like viscosity, shear stability, high- and low-temperature performance, water resistance and volatility. Lubrication science seeks to optimize a lubricant’s performance by managing these properties using different base oils […]

Top 5 Skid Steer Maintenance Tips _by David Hilgendorf|September 29, 2023 Skid steers are built for tough construction, excavation, agricultural and other professional projects. Whether you’re clearing land, moving rocks or tearing down a wall, a skid steer is an excellent piece of equipment for many different jobs. But these nimble machines can be expensive […]

thermal runaway occurs when viscosity drops out and wear increases

How Often Should I Change Differential Fluid? Fluid change intervals depend on your vehicle, driving conditions and gear oil quality. Save time and cash first by improving the situation with this differential fluid solution! _by David Hilgendorf|Feb 26, 2023 A differential is a set of gears that allows a vehicle’s driven wheels to revolve at […]

New European oils for 2023 0W-30 and 10W-60

New AMSOIL Synthetic European Motor Oil Viscosities A new 10W-60 and 0W-30 for several BMW, Volkswagen and other fancy European cars. _by Brad Nelson|June 13, 2023 Those who know, know. The sophisticated engineering, finely-tuned performance and artistic styling of European cars can turn a daily commute into a grin-inducing experience. The design of these vehicles […]

EZ marine lower gear lube service

Service Marine Lower Units to Prevent Water Damage Preventing rust and other water-related problems in marine lower units. Most other Marine Gear Oils fail to make the grade. We learn more on that from our own customers when they make the switch. by David Hilgendorf|April 24, 2023 Water and gear lube don’t mix. Unfortunately, you […]