The Fleetguard FF5825NN fuel filter alternative is Steinberg FF006, a direct OEM-grade equivalent for the Cummins ISX, ISX15, and X15 primary fuel filter position. Same 5-micron media. Same 4.74-inch outer diameter. Same M16x1.5 threaded mount. Same Cummins spec sheet on both labels. The whole reason "alternative" exists as a search term is that buyers already know what FF5825NN does — what they want is whether someone else's part does the same job for less money in the same delivery window.
What FF5825NN is and what it fits
The FF5825NN is the primary fuel filter for Cummins ISX (EPA 2010 onward), ISX15, and X15 engines through current Stage IV production. It sits engine-mounted, upstream of the high-pressure injection pump, doing the last fine-particulate work before fuel reaches the rail. The "NN" suffix marks Fleetguard's NanoNet synthetic media: better dust-holding capacity than the older paper-media FF5776 it largely replaced.
The trucks running this filter are the Class 8 long-haul backbone of the US fleet: Kenworth T680 and T880, Peterbilt 579, Volvo VNL when ordered with Cummins, Freightliner Cascadia with the Cummins option, Mack Pinnacle with the X15, and International LT and ProStar configurations. Roughly 4.74 inches (120 mm) in outer diameter, 5.6 inches (143 mm) tall. Standard threaded mount, no special tools.
Spec parity: where FF5825NN and FF006 are identical
Cross-reference filters share the engineering spec by design. The whole point of an aftermarket equivalent is that it drops into the same housing, traps the same micron range, and protects the same injection system. Where FF5825NN and FF006 differ is commercial: brand, supply chain, and pricing tier, not engineering.
Both filters share these specifications:
- Filter type: spin-on primary fuel filter, synthetic media
- Micron rating: 5 µm absolute (β₁₀₀₀ per ISO 19438)
- Outer diameter: 4.74 in (120 mm)
- Height: 5.6 in (143 mm)
- Thread: M16 x 1.5
- Service interval: 30,000–50,000 miles, depending on duty cycle and fuel quality
- Engine fit: Cummins ISX, ISX15, X15 primary fuel position (EPA 2010 through current Stage IV)
Where they differ
| Fleetguard FF5825NN | Steinberg FF006 | |
|---|---|---|
| Brand position | OEM (Cummins-owned) | Aftermarket OEM-grade |
| Pricing tier | OEM dealer list (~$35–55/unit) | Wholesale fleet (~$18–25/unit) |
| Supply chain | OEM dealer network | Direct from Hodgkins, IL |
| Stocked for | Warranty-period engines, dealer service | Fleet operations, mixed-age units |
| Shipping | Dealer lead time | Same-day before 2 PM CT |
| Payment terms | Standard | NET-30 for qualified fleet accounts |
FF5825 vs FF5825NN: what the "NN" suffix changed
The plain FF5825 was Fleetguard's earlier spec for the same engine position, using cellulose paper media. Cummins reissued the part as FF5825NN once the NanoNet synthetic media was qualified for the X15's high-pressure common-rail. The NN version holds more particulate before filter restriction triggers an ECM pressure-rail code, runs longer in cold-weather service where fuel quality drops, and protects the injection system at the same micron rating with better margin against premature plugging. If you have a 2015+ X15 in service, FF5825NN is the current spec. The plain FF5825 still appears in inventory occasionally; treat it as superseded.
What brand of filter Cummins uses, and why that matters for the swap
Cummins owns Cummins Filtration, which manufactures the Fleetguard line. When a new Cummins engine ships from the factory inside a Kenworth, Peterbilt, Freightliner, or any OEM truck builder, the service kit specifies Fleetguard part numbers as the manufacturer-recommended filter. That makes Fleetguard the OEM-branded option. Aftermarket equivalents from Donaldson, Baldwin, WIX, Luber-Finer, and Steinberg meet the same spec but are not Cummins-branded. For warranty-period engines, that distinction can matter to the operator's risk tolerance. For older units past warranty, the spec is what matters and the brand on the box does not.
Cross-reference: every FF5825NN equivalent in one table
The full industry cross-reference for Fleetguard FF5825NN, sourced from manufacturer catalogs and Cummins QuickServe documentation:
| Manufacturer | Part number |
|---|---|
| Steinberg (aftermarket) | FF006 |
| Donaldson | DBF6776 |
| Baldwin | BF46129 |
| WIX | WF10515 |
| Cummins (OEM) | 5365988 |
| Fleetguard (predecessor) | FF5776, FF5686 |
If the part number on your invoice or your fleet ERP system is not in this table, run it through the Steinberg cross-reference search. Updated continuously as Cummins issues running changes and aftermarket brands renumber.
Why fleet operators switch to Steinberg FF006
The Fleetguard FF5825NN at OEM dealer pricing runs $35–55 per filter, depending on quantity, dealer relationship, and region. Steinberg FF006 lands in the $18–25 range at fleet pricing, same spec, same fitment. For a fleet running 50 trucks on 30,000-mile fuel filter intervals, that is roughly 100 filter changes per year. The arithmetic at fleet scale is not subtle.
Where the savings stop being abstract is the moment a wrong-spec or counterfeit filter passes a 50-micron particle into the high-pressure injection pump. The HP pump on a Cummins X15 does not announce its complaint. It scores the cam bore quietly for a couple thousand miles, then grenades on a Wednesday afternoon outside of Terre Haute with a load that has to be in Chicago by morning. Pump replacement runs roughly $4,200 for the part plus 6 to 8 hours shop labor at $185 per hour, before any tow cost or rental tractor for the load. Spec discipline is the cheapest line item in fleet maintenance, and the only one that pays for itself the day nothing goes wrong.
What ships and how
Steinberg FF006 ships from our Hodgkins, Illinois warehouse, same-day for orders placed before 2 PM CT, with NET-30 payment terms for qualified fleet accounts. Fleet sourcing inquiries: email sales@steinbergus.com with your fleet size, the engine generations you operate, and your current OEM dealer pricing for comparison.
For the broader Cummins X15 catalog (water separators, lube filters, air intake), see the Cummins ISX 15 / X15 Filters collection. For the quick FAQ-format answers on FF5825NN cross-reference and micron rating, see our FAQ on FF5825NN cross-reference and the FF5825NN micron rating breakdown.
Browse the Cummins ISX 15 / X15 Filters collection →
Sources & further reading
- Cummins QuickServe Online — OEM service documentation for ISX, ISX15, and X15 engines, including fuel filter part numbering and service intervals.
- Fleetguard product catalog (Cummins Filtration), FF5825NN spec sheet, NanoNet media technology overview.
- TruckersReport heavy-duty diesel forum threads — operator-reported field data on FF5825NN service life under various duty cycles and fuel quality conditions.