BD28 Dual-Flow Lube Spin-On Filter

Contains: Anti-Drainback Valve; 20 PSID By-Pass Valve
Fits: Ford Light-Duty Trucks
Replaces: Ford E5TZ-6731-A
Thread: M26 x 1.5
OD: 3-11/16" (93.7mm)
Length: 5-3/8" (136.5mm)
Integral Gasket: G381-A


A common misconception is that regular oil filter replacement is sufficient to keep oil clean. But standard spin-on full-flow oil filters remove only the largest solid contamination particles, typically only down to 100 to 20 microns.

By providing a finer level of particle filtering – often down to 10 microns, or even smaller – bypass oil filters provide exceptional purification for oils in engines, transmissions, and hydraulic systems.

On engines, bypass filtering systems are typically plumbed into the standard lubricating oil circulation system, where they continuously filter a diverted portion of the oil. Bypass filter systems may be factory-installed or added as an aftermarket modification.
Unlike the main oil filter, the bypass filter doesn’t need to handle the full flow of engine oil, so its flow rate can be relatively low, allowing it to have a much finer pore size with greater filtering capability.
(Small pores would quickly get clogged in a full-flow filter, at which point built-in safety features would take the filter out of the circuit, leaving the engine vulnerable to damage.)

Dual-flow filters are designed with both full-flow and bypass oil filter functions within the same canister.