Despite their seemingly different names, diesel and jet fuel share many similarities but are different and optimised for different purposes.
Jet fuel, such as Jet A, is designed for turbine engines in aircraft, with low viscosity and lubricity to ensure smooth operation. Diesel fuel, on the other hand, is tailored for compression-ignition engines and has higher lubricity to protect engine components.
While jet fuel can sometimes be used in diesel engines—particularly in airport support vehicles—it can lead to long-term wear on components like fuel pumps and injectors if proper additives aren't used, due to its lower lubricity and lack of lubrication properties.
Diesel can work in jet turbine engines during emergencies, but it is rarely used because of its heavier weight (5-10% more), which can impact aircraft performance, and its higher viscosity, which increases in colder temperatures at altitude and may cause fuel lines to clog.
