DEF supply for fleets: a practical guide

Diesel exhaust fluid (DEF) is required for the selective catalytic reduction systems on modern diesel engines. Run out, and vehicles derate or stop — so consistent supply is not optional.

For a fleet, the challenge is scale: DEF needs to be available wherever your trucks and equipment fuel up, across yards and routes, without someone tracking every jug and bulk tank by hand.

The fix is to manage DEF the same way you manage fuel: bulk delivery to your yards, automated replenishment so tanks stay ahead of demand, and one account so you can see consumption across the fleet.

Harlan brings fuel and DEF onto one platform with local fulfillment, so every vehicle stays compliant and moving — and you get clear reporting on what each site is using.