Why Your Injectors Are Wearing Out Faster Than They Should
Since the switch to ultra-low sulfur diesel, injector and pump wear has become a more common complaint than it used to be — and the fuel itself is part of the reason why. ULSD has less natural lubricity than the diesel fleets ran on before the sulfur reduction, and it absorbs water more readily, which only makes the wear worse.
Why lubricity matters more than it sounds like it should
Fuel isn't just fuel to the injection system — it's also the lubricant for the pumps and injectors that move it. Poor lubricity, measured by HFRR wear scar testing, means more friction and faster wear on parts that are expensive and time-consuming to replace. EPA's maximum allowed wear scar for ULSD is 520 on the HFRR scale, but heavy-duty industry groups recommend a tighter 460 for what they consider truly premium fuel — most fuel at the pump lands somewhere in between.
Fuel with poor lubricity isn't failing a spec test. It's quietly grinding down the parts it's supposed to protect.
Closing the gap
A quality lubricity additive can bring wear scar performance down well below even the stricter industry recommendation — some formulations get below 350 on the HFRR scale, meaningfully better protection than pump fuel alone provides. For a fleet running high mileage, that's fewer pump and injector replacements over the life of the equipment.
The Takeaway
ULSD's lubricity trade-off is a known, measurable gap — and it's one of the more straightforward problems a fuel additive can close.