Donaldson P555776 Fuel Filter | Cummins X15, ISX & Heavy-Duty Diesel Engines

Donaldson P555776 Secondary Fuel Filter for Cummins X15 & ISX Engines

The Donaldson P555776 Fuel Filter is a premium secondary diesel fuel filter engineered to provide superior fuel cleanliness and injector protection for Cummins X15, Cummins ISX, and other heavy-duty diesel engines. Designed to remove fine contaminants before they reach sensitive fuel system components, the P555776 helps maximize fuel system reliability, engine performance, and equipment uptime.

Modern common rail diesel engines require exceptionally clean fuel to operate efficiently. The Donaldson P555776 delivers high-efficiency filtration that helps protect expensive fuel injectors, fuel pumps, and emissions system components from harmful contaminants that can lead to reduced performance and costly repairs.

Trusted by fleets, owner-operators, repair facilities, and diesel performance shops across North America, the P555776 is a proven solution for maintaining peak fuel system performance in demanding operating environments.

Key Features

• Premium secondary fuel filter
• High-efficiency contaminant removal
• Protects fuel injectors and fuel pumps
• Designed for high-pressure common rail fuel systems
• Maintains proper fuel flow
• Helps improve fuel system reliability
• Heavy-duty commercial-grade construction
• Spin-on design for easy installation
• Fleet-proven Donaldson filtration technology

Specifications

• Part Number: P555776
• Brand: Donaldson
• Filter Type: Secondary Fuel Filter
• Style: Spin-On
• Outer Diameter: 4.65"
• Length: 8.54"
• Thread Size: 1-14 UNS
• Application: Cummins X15 & ISX Fuel Systems

Benefits of Replacing Your Fuel Filter

• Protects expensive fuel injectors
• Maintains proper fuel pressure
• Improves fuel system efficiency
• Reduces injector wear
• Improves engine performance
• Helps maximize fuel economy
• Reduces maintenance costs
• Supports longer component life

Common Applications

• Cummins X15 Engines
• Cummins ISX Engines
• Freightliner Cascadia
• Kenworth T680
• Kenworth W990
• Kenworth W900
• Peterbilt 579
• Peterbilt 389
• International LT Series
• Western Star Trucks
• Fleet & Vocational Truck Applications

Major Cross Reference Numbers

The Donaldson P555776 crosses with many popular OEM and aftermarket fuel filters used throughout the heavy-duty trucking industry:

• Cummins 4934845
• Cummins 5472251
• Cummins 3959612
• Cummins 3331516
• Fleetguard FF5488
• Fleetguard FF5776
• Fleetguard FF63054NN
• Baldwin BF46065
• Baldwin BF46064
• WIX WF10176
• NAPA 3676
• Luber-Finer LFF5776
• Donaldson P550774
• Donaldson P583177
• Carquest 86776
• Alliance ABPN10GFF5776

Always verify fitment by engine serial number and OEM requirements before ordering. Some applications may use multiple filter configurations depending on fuel system design.

Why Secondary Fuel Filtration Matters

Secondary fuel filters serve as the final line of defense before fuel reaches high-pressure injectors. In modern diesel engines such as the Cummins X15 and ISX, injector tolerances are extremely tight, making proper filtration critical to fuel system longevity and engine reliability.

Replacing secondary fuel filters at recommended service intervals helps prevent injector damage, fuel pressure issues, hard starting conditions, and expensive fuel system repairs.