Full-flow Oil Filter — a one-system approach is not enough!

Full-Flow Lube Filtration


Full-Flow-Lube-FiltrationContamination control is a crucial part of a proactive maintenance strategy. You need effective oil filtration to keep your engines in operation. There are two (2) basic types of oil filtration systems: (1) Full-flow oil filters (primary oil filter) and (2) Bypass oil filters (secondary oil filter). Particles contaminating the lube oil are a common cause of engine failure. 

Particle contamination can come from several different sources: built-in contaminants (cylinders, fluids, hoses and pipes, reservoirs, valves, etc), generated contaminants (assembly of system, break-in of system, operation of system, fluid breakdown), external ingression (reservoir breathing, cylinder and rod seals, bearing seals, component seals), and contaminants introduced during maintenance (disassembly/reassembly, makeup oil). When the lube oil is contaminated, problems will eventually pile up. Contamination changes the oil properties, which will deteriorate and cause engine problems.

A one-system approach is not enough!

A bypass oil filter works independently of the full-flow oil filter and adds an extra layer of engine protection. The combination of full-flow oil filters and bypass oil filters helps improve operational costs, lowers the total cost of ownership (TCO), and extends equipment lifetime. 


What is a full-flow oil filter?

What-is-full-flow-oil-filterA full-flow oil filter (or primary oil filter) is a type of lube oil filter that is standard on most engines. If you have only one lube oil filter on your engine, it is most likely a full-flow filter design. The lube oil that goes through this filter lubricates the entire engine. This oil filter removes the larger-sized particles of contaminant from the lube oil that may harm the engine. A full-flow oil filter must provide low restriction to oil flow while having a high degree of “single-pass efficiency.”  The filter must remove engine-damaging soot, dirt, dust, and grit from the oil the first time around. 

Every lube oil filter needs to balance three (3) key design characteristics effectively:
Efficiency (contaminant capture from particulate to sludge)
Capacity (contaminant holding space)
Restriction (minimal oil flow restriction)

The full-flow oil filter (or primary oil filter) is designed to protect the engine (screening the oil). The full-flow oil filter is designed to keep out large contamination particles (typically 35-40 microns and larger). The purpose is not to keep the lube oil clean at very low ISO cleanliness levels but to keep large particles from damaging the lubricated components. A relief valve (bypass valve) is built into the filtering system to ensure a supply of oil to lubricate the engine under all conditions. The bypass valve is present to open at a given pressure drop and divert the flow past the filter element. This prevents a dirty filter element from restricting flow excessively. This filter relief valve could be located in the engine or oil filter base (attached to the engine) or in the full-flow filter. 

What happens when the full-flow oil filter is blocked?

increase-engine-oil-filtration-efficiencyThe full-flow filter media is generally very porous. When the media becomes blocked with contamination, the internal bypass valve will open, allowing unfiltered lube oil to exit the filter and reach the equipment. Under normal operating conditions, this valve is closed. However, this valve will open and supply oil directly to the engine whenever the full-flow filter becomes plugged with contaminants and the full-flow filter is too restrive to oil flow. When this occurs, unfiltered, contaminated dirty oil bypasses the filter and flows directly to the bearings. Manufacturers believe it is better to supply unfiltered dirty oil to the bearings than to burn them out by lube oil starvation.  

The full-flow oil filter is limited to a finite particle size because finer filtration will decrease the oil’s flow rate. As the full-flow oil filter accumulates more contaminants, the filter will increase the pressure differential, causing additional pressure losses. 

How do you increase engine oil filtration efficiency?

Adding a bypass oil filter to your lube oil filtration system will increase efficiency when used in parallel with a full-flow filter. A bypass oil filter only requires a fraction of the oil flow for sufficient flow rates within the oil system. Centrifugal bypass filters have proved helpful in extending the primary full-flow oil filter life. Bypass centrifugal oil filters can increase the number of operating hours before the primary full-flow oil filters become restricted. 

Improve filtration for less wear and a cleaner engine!

bypass-oil-filterEngine oils acquire a significant amount of wear metals from moving parts on the engine and soot from the combustion process. Engine lube oil provides lubrication to all sliding parts of the engine, sealing between the ring and the cylinder wall, cooling the pistons, and keeping engine components clean. This is a demanding service for the engine lube oil. The two-three micron (2-3 μm) gap between the ring and the cylinder wall provides a seal to keep combustion gases from the crankcase. As the contamination builds up, particles wedge between the two (2) surfaces and break the oil seal, allowing combustion product blow-by and increasing lube oil usage.

This will increase the wear to the surfaces due to abrasive bridging. The contamination bridge also creates wear on the bearing surfaces, camshaft, and gears. Proper lubrication is critical to successful engine operation. A centrifugal bypass filter will remove and capture the harmful contaminants and particles from the oil. Centrifugal bypass filters offer better filtration efficiency than standard bypass oil filters, improved engine cleanliness, and a longer component life. 


What are the different types of full-flow oil filters?

Engines are tasked with performing a wide range of functions. While manufacturers produce numerous filter housings designed for different engines, there are fundamentally just three (3) primary types of oil filtration systems. They are spin-on oil filters, cartridge oil filters, and automatic backflushing (self-cleaning) oil filters.

Spin-On Oil Filter

cartridge-spin-on-oil-filtersThe spin-on oil filters are one of the most recognized engine parts. A spin-on filter consists of several parts, including the steel canister, drain-back valve, bypass valve, and gasket. The spin-on filters are easier to replace but make a bigger mess. 

Cartridge Oil Filter

Instead of replacing the complete filter, with a cartridge oil filter, only the dirty filter element has to be renewed. Oil filter cartridges are available for all oil filters with removable housings. The pressure drop across the replaceable paper filter cartridges is one parameter indicating the contaminant level. The higher the dirt content in the lube oil, the shorter the periods between filter cartridge replacement and cleaning. A coalescing cartridge filter is used to separate water from the oil. Since some cartridge oil filters are made entirely of cellulose filter media and plastic, they can be incinerated instead of tossed in the trash. Cartridge oil filters allow the oil to drain from the filter housing before taking apart the cartridge oil filter for filter changing.

Automatic Backflushing (Self-Cleaning) Oil Filter

Automatic-Backflushing-Oil-FilterThis is an ecologically sensible solution that saves materials and disposal costs. The automatic backflushing (self-cleaning) oil filter has a filter element with very fine metallic mesh. The complete filter assembly comprises a filter housing, filtering unit, and electric/hydraulic motor. The filter elements are divided into segments, always doing full-flow filtration, and one (1) is under back flushing. There is an electric or hydraulic motor that keeps rotating the elements so that each element gets backflushed periodically.

The backflushed oil with solids from the full-flow oil filter is returned to the oil sump. Integrating a centrifuge filter with your automatic backflushing full-flow oil filter will remove the contaminants before returning to the oil sump. The automatic backflushing oil filter is designed for continuous backflushing, eliminating the need for manual cleaning. The sealed automatic backflushing oil filter does not need to be opened for two (2) years (12,000 hours). This eliminates the need for the disposal and replacement of used oil filters. Automatic backwash filters are cost-worthy and more efficient than cartridge oil filters.


Best Bypass Oil Filter System (Secondary Filtration)

IOW-GroupContamination control is a key part of a proactive maintenance strategy. A bypass oil filter works independently of the full-flow oil filter and adds an extra layer of engine protection. The best bypass oil filter system on the market is the IOW Group centrifugal bypass oil filter. The high-efficiency disc-stack centrifuge is efficient at keeping a low contamination level. Investing in an IOW Group centrifugal bypass oil filter is a relatively small cost with substantial benefits. Bypass oil filter systems (secondary filtration) are set up as a kidney loop system using the engine’s lube oil pump pressure or a designated feed pump. To learn more, visit our Bypass Oil Filtration is the answer! blog page.

A one-system approach is not enough! Adding a bypass oil filter to your lube oil filtration system will increase separation and filtration efficiency when used in parallel with a full-flow filter.

The IOW Group bypass oil liters come standard with bowl disc technology and your choice of external monitoring units. The IOW centrifuges are the market leaders in separation efficiency. To learn about bypass oil filter systems, visit


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