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Automotive experts agree dirt is the number one cause of engine wear. In fact, analysis by Federal-Mogul Corporation reports that 43.4 percent of all engine bearing distress is caused by dust and dirt contamination of the motor oil.

Dirt particles are extremely abrasive. They consist of razor-like flakes of road dust and airborne grit drawn into the engine through the intake manifold. Along with manufacturing scarf and wear metal particles generated inside the engine, these particles are carried by the oil into the precision clearances between bearings and other moving parts, where they grind and gouge surfaces, altering clearances and generating more abrasive debris.

As this wear cycle continues, precision components become sloppy and fatigued until they fail altogether. Filtration, both oil and air, is the key to preventing costly engine repairs caused by dirt, removing contaminants by trapping and holding them outside the system of oil circulation.

In order for a filter to be truly effective, it must be able to capture contaminants of all types and sizes. AMSOIL offers a complete line of sophisticated filtration products designed to offer the best protection available against virtually all harmful engine contaminants.

Early automobiles did not have any sort of Oil Filtration System and many cars well into the '60s offered oil filters only as an extra-cost option. It was common practice in those early days to change the engine oil every 500 to 2,000 miles (800 to 1,600 kilometers).

Later, when drilled crankshafts and pressure lubrication systems became common, some kind of oil filtration was necessary in order to protect the oil pump from damage and excessive wear. Early filter designs were often crude set ups using steel wool, wire mesh or metal screens placed in the oil pump intake. Many of these early oil filter designs were cleanable and reusable. (One very popular car that came with a built-in oil strainer but not a filter was the original VW Beetle.)

The very first modern oil filter was introduced in 1923, invented by Ernest Sweetland and George Greenhalgh. They were granted a patent in 1929 and named the new product "PurOlator" - a portmanteau of the words "Pure Oil Later".

The original Purolator featured an upright series of seven twill-weave cloth covered perforated plates encased in a heavy-duty cast canister. It also had a sight feed glass on one side, enabling the owner to see the oil flow and change the entire unit when the flow slowed to a trickle.

The "oil cleaners" soon became standard on many popular automobiles of the day. Over the years, innovations in oil filter technology continued. In the late 1930's, cotton waste material was introduced as filtration media, providing the first replaceable filters. Woven fabrics were also used in some filter designs.

Prior to 1943, most oil filters were of the bypass variety, only filtering about 10% of the oil at a time. But the rigors of war-time use showed that something better was needed for engine protection and the first "full-flow" filtration system, capable of filtering 100 percent of the motor oil, was introduced later that year.

Three years later, in 1946, PurOlator, working with Chrysler Corp., patented the first “pleated paper” oil filter element, a technology still widely used as part of today’s oil filters. As disposable filters became the norm and interest in saving production costs increased, materials such as pleated paper and cellulose became the filtration media materials of choice and are still widely used in today's oil filters.

Then in 1948, PurOlator developed the first Original Equipment (OE) "block mounted" oil filter, an important advancement because now the filter was on its way to becoming a part of the engine. Prior to this, many filters were mounted elsewhere in the engine compartment. But even with this block mounted configuration, the filter system continued to consist of a replaceable filtration element and a permanent canister to hold the element.

James A. Abeles saw enough potential in the PurOlator to convert a New York City garage into a company called Motor Improvements Inc., developed primarily to manufacture PurOlator filters. The Maxwell Chalmers Company also saw promise in this new product, installing a PurOlator on a Maxwell automobile which was test-driven on a round-trip from Detroit to the West Coast in 1924. Also in 1924, Walter P. Chrysler introduced the first vehicle to carry his name, the Chrysler Six. A PurOlator oil filter was standard on the new Chrysler.

The longer oil drain intervals, cleaner oil and reduced engine wear offered by the PurOlator ensured endorsement by the automotive industry, and they soon became standard on many popular automobiles of the day, including Studebaker, Pierce Arrow, Hupmobile, Peerless, Cadillac, Oakland, Gardner, Moon, Jordan, Buick and Dodge.

In 1949, PurOlator Products, Inc. had facilities in Newark, New Jersey and Windsor, Ontario, Canada. At that time, the company offered a range of oil filters that fit cars and trucks from a 1931 LaSalle up to most new 1949 models, either as original equipment replacements or retrofit installations.

The OE replacements were mostly Purolator N or T Series models, while most of the installation kits used the latest P-Series Micronic canisters and elements. A heavy-duty model called the P-3000, designed for vehicles with crankcases holding over 25 quarts of oil, used two filter elements inside its extra-tall canister.

In non-OE applications, the filter size recommendations were based on the crankcase capacity of the vehicle being retrofitted. All N-1500 and P-700 series Purolator's were recommended for crankcase capacities of 6 quarts or less. All N-1900 and P-900 models were for 6- 14 qt. crankcases. Vehicles with 14-25 qt. crankcases were suited to N-2900 and P-2900 filters. Finally, vehicles with crankcases of 25 qts. or more were best suited to N-3000 and P-3000 filters.

Also is In 1949, PurOlator also developed a new Wing-Nut Type Micronic Filter (see images below) that allowed motorists or mechanics to check the filter element as quickly and easily as checking the oil. This design required no tools to unscrew the wing nut on top and lift off the cover. The P-40 filter inside came out with the cover so it could be checked for muck.

PurOlator did a good job of promoting the Wing-Nut Top as a "money maker" for its dealers. A 1949 trade advertisement claimed that the new P40 Purolator Micronic Refill had "5 times the filtering area of old-style filters" and "removed 290% more sludge."

The savvy mechanic could take advantage of the claims that the P-40 trapped more sludge and was easily removable by whipping out the dirty filter each time a customer drove in. "This muck in an oil filter can mean money in your pocket!" said the ad’s headline in bold type. "Show it to your customers for more Purolator sales."

As often happens in automotive history concerning who exactly did what first, there is some dispute as to who came out with the first modern "spin-on self-contained oil filter" - PurOlator or WIX.

WIX claims to have invented the easily detachable, disposable "spin-on" oil filter in 1954, one year before the PurOlator one, replacing cartridge-type filters which had to be placed in a special housing or canister. Automotive historian Matt Joseph believes Chrysler may have been first to use them.

The spin-on filter subsequently became the prevalent design, though not always as standard equipment. This type of filter is now used almost exclusively in modern passenger cars and in recent years has become more prevalent in heavy-duty vehicles.

Still, during the 1950s the use of oil filters on cars varied. For example, as early as 1953, a full-flow oil filter was listed as standard equipment for the Lincoln V-8, but a canister-type oil filter was optional equipment on the 1956 Ford. The 1957 Mercury included a spin-on oil filter at no extra cost. All 1958 Buicks in all series came with an oil filter. However, if you bought a 1959 Chevrolet, the car and engine you ordered determined whether you would get an oil filter and what type it would be.

Chevrolets with the Hi-Thrift 6 engine offered a "by-pass" type oil filter as an extra-cost option. A full-flow oil filter was optional at extra cost on 1959 Chevrolets with V-8 engines, unless the car had Rochester fuel injection. In that case, the full-flow filter was standard. And if you ordered a car with a special 348-cid "Turbo Thrust" V-8, the installation of an oil filter was listed as a mandatory option.

The technology progressed throughout the 1960s and spin-on oil filters soon became standard on virtually all American, European and Japanese automobile designs.

By the early 1960s, there were dozens of different oil filtration system designs and a myriad of trade names. You could find ads in pulp magazines offering magnetic filters, "snow cone" shaped filters, bronze filters and others. But in a more realistic sense, at that time there were two basic types of practical, mass-produced oil filter materials: "pleated paper" and "activated clay".

Detergent oils had come into use by 1961 and, as most hobbyists know, these tended to break down the sludge deposits that PurOlator used to count on to sell Wing-Nut filters. Detergent oil would hold these dirt particles in suspension and, if everything went right, the "pleated paper" type filter would allow only microscopic particles to pass through it. In theory, at least, the filter would snag any sludge that was large enough to hurt the engine.

In contrast, the "activated clay" filter would take out just about every bit of dirt. In fact, it would sometimes leave the oil looking clean enough to scare a lab tester. One problem with activated clay filters is that they would also filter out some expensive oil additives. The pleated paper filters did a good job of keeping the engine safe as long as the motorist made sure the filter was changed in accordance with recommended drain intervals.

In order for an oil filter to be truly effective, it must be able to capture contaminants of all types and sizes. Efficiency is the oil filter's ability to capture contaminants. The more efficient a filter is, the more contaminants it will remove from the oil.

AMSOIL Ea® ("Ea" stands for "Absolute Efficiency") full-flow oil filters (EaO) have one of the best efficiency ratings in the automotive/light-truck market. They provide a filtering efficiency of 98.7 percent at 20 microns, while competitive filters demonstrate efficiencies as low as 51 percent (see comparison chart below).

Full-flow Oil Filters install directly into the line of oil circulation. The oil passes through the filter as the oil journeys between the oil pump and the engine (more on the workings of a full flow filter later). A full-flow filter must be able to remove and hold dirt and other contaminants without obstructing oil flow to the engine.

An important thing to mention is the efficiency rating of a full-flow oil filter. That efficiency rating is simply a measure of the percentage of ~20-micron dirt particles that the filter can capture over a certain duration.

Because they use a thin layer of porous filter paper, most filters on the market compromise the filtration of finer particles. Such filters have almost no extended cleaning ability since they have a low capacity for storing dirt and other contaminants.

These "surface-type" paper filters quickly become restricted as debris builds up on the paper surface, forcing the filter by-pass valve to open and allows unfiltered oil into the engine (more on filter by-pass valves later).

An Oil Filter’s capacity refers to the amount of contaminants it can hold and still remain effective. Proper oil flow is essential to keeping the engine's internal parts lubricated at all times.

AMSOIL Ea® Full-Flow Oil Filters feature advanced full-synthetic media that traps and holds a greater amount of small, wear-causing contaminants compared to conventional filters. They provide extended service intervals for increased convenience, while helping reduce engine wear. They are ideal for use in conjunction with our premium extended drain full synthetic motor oils such as our Signature Series and Extended Life lines of 100% synthetic motor oils.

Proper oil flow is essential to keeping engine parts lubricated at all times. Ea® Oil Filters' synthetic fibers are much smaller than the fibers used in traditional cellulose filters, allowing them to provide significantly lower flow restriction.

During cold-temperature warm-up periods, an Ea® Oil Filter allows the oil to flow through the filter more easily than a typical cellulose fiber filter does. Lower restriction leads to a decrease in engine wear.

AMSOIL Ea® Full-Flow Filters are made with premium-grade full-synthetic media. The strictly controlled processing of this media ensures accurate filter construction and is what allows Ea® Oil Filters to deliver higher capacity and efficiency along with better durability.

Ea® Filters' full-synthetic media technology is resin-free to resist degradation from hot oil. It uses a wire screen backing that is pleated with the media for superior strength.

They are constructed with HNBR gaskets that are fully tested to extreme distances in numerous severe environments and feature fully tucked seams, a molded element seal, roll-formed threads and a long-lasting, premium-grade silicone anti-drain-back valve. (see images below)

There are actually two types of full-flow oil filters: the Canister/Spin-On type and the Cartridge type.

Your engine’s Oil Pump pushes oil into the Filter - which is sealed to your engine’s oil filter housing - through a number of radial holes in the filter’s metal 'base plate'. The pressure generated by that pump is enough to push an 'Anti-drain-back Valve' - which sits just on the other side of the base plate - out of the way, at which point oil can enter the Filter.

Once in the Oil Filter, the oil surrounds a cartridge, which consists of a center tube (usually-metal) surrounded by cellulose-based or synthetic pleated fibers, sealed off by metal, plastic, or fiber end-caps.

Once oil has passed through the base plate holes, through the anti-drain-back valve, and has surrounded the filter element, it passes through the pleated medium, through the holes in the center tube, and back up through the exit at the top of the filter. (the images below illustrate the different types of full-flow filters - Canister and Cartridge)

Two very important parts of an oil filter are the 'Anti-drain-back Valve' and the 'By-pass Valve'. (see images above)

The Anti-Drain-Back Valve makes sure the filter traps oil when the engine isn’t running. It’s essentially a nitrile or silicone one-way check-valve that prevents oil in a filter - particularly one that’s mounted sideways or upside-down - from flowing back into the sump. This means, when you come to start your engine back up, you’ll get instant oil pressure to lubricate internal engine parts (i.e., you won’t risk a "dry start").

To prevent a plugged oil filter from starving the engine of lubrication, oil filters have a built-in safety device called a By-pass Valve. The By-pass Valve's job it is to allow the oil to by-pass the filter cartridge, flowing unencumbered by the filtration material, to provide adequate engine lubrication under all conditions.

When the differential pressure across the oil filter element exceeds a predetermined value, like those that might occur if the filter element has reached its capacity (like if it’s been left on a car for too long, and has clogged with dirt and other contaminants) or if the oil’s viscosity is too high (thick - especially in cold conditions), the By-pass Relief Valve opens so oil can continue to flow to the engine. However, when the By-pass Relief Valve is open no filtration occurs.

Also inside an Oil Filter are leaf or coil springs. Those springs simply act to push the cartridge up against the anti-drain-back valve.

Another very important feature of a Filter is the 'gasket'. It has to seal the oil in the system for thousands of miles, in an atmosphere of heat and vibration. Gasket quality is very important, and low-priced filter manufacturers tend to use cheap low-quality gaskets that get hard and brittle after just a few thousand miles. Leaks or worse can result.

By-pass Oil Filtration features a secondary filter with the purpose of eliminating nearly all contaminants from motor oil.

By-pass filters have high capacities and eliminate much smaller particles than full-flow filters, including soot. They reduce engine wear and increase oil volume, but their high efficiencies mean they also have higher restriction and must be used in conjunction with a full-flow filter.

AMSOIL Ea® By-pass Oil Filters operate by filtering oil on a "partial-flow" basis. They draw approximately 10 percent of the oil pump's capacity at any one time and trap the extremely small, wear-causing contaminants that full-flow filters can't remove.

By-pass filters have a high pressure differential, causing the oil to flow through them very slowly and allowing for the removal of smaller contaminants. It is called by-pass filtration because the oil flows from the by-pass filter back to the sump and by-passes the engine. (see images below)

This continual process eventually makes all of the oil analytically clean, reduces long-term wear and can dramatically extend drain intervals.

Because oil must be filtered quickly while removing most of the particles in the oil, the average full flow filter can only trap particles as small as 20 microns. With an efficiency rating of 98.7 percent at 2 microns, AMSOIL Ea® By-pass Oil Filter provides the best possible filtration protection against internal engine wear and degradation of the motor oil.

The superior construction of AMSOIL Ea® By-pass Oil Filters provides better sealing and increased longevity along with superior corrosion resistance. EaBP® Filters have a marine powder coated exterior and their zinc-dichromate base plates increase rust protection. They also have a nitrile HNBR gasket and an orange silicone anti-drain-back valve.

AMSOIL’s high-efficiency by-pass filter element is also a soot removal device given that it will filter out particles down to 2 microns.

In fact, these filters will remove 39 percent of soot contaminants less than 1 micron in size. Soot removal efficiency increases approximately 10 to 14 percent when the EaBP® Filter is used in conjunction with a standard full-flow filter.

Ea® By-Pass Filters use a synthetic/cellulose sandwiched media (see illustration below). The inner layer of the element is composed of a highly efficient cellulose media covered with a full synthetic media outer layer.

AMSOIL Ea® By-Pass Oil Filters typically filters all the oil in the system several times an hour. At normal operating RPMs it will filter all of the oil in a typical five quart sump in less than 10 minutes. The continual filtering process eventually makes all the oil analytically clean, reducing long-term wear.

The increased fluid system capacity and filtration life provides improved oil cooling and ensures that equipment constantly runs on clean oil. Engine efficiency is increased, providing extended engine life. By cleaning the oil so thoroughly, the EaBP® Filter not only prolongs engine life but also the life of the oil itself. With the Ea® By-Pass Filter, oil changes can be extended well beyond the normal recommended oil drains intervals, in some cases, almost indefinitely.

The AMSOIL Dual-Guard® By-Pass Oil Filter links 2 AMSOIL Ea® By-Pass Filter Elements together for engines with sump capacities greater than 20 quarts.

Available only from AMSOIL, the Dual Remote Oil Bypass Filtration System replaces conventional full flow filters. Mounting in any convenient location in the engine, the Dual Remote Oil Bypass Filtration System gives full flow and by-pass oil filter protection (see images below). With the AMSOIL Dual Remote Oil Bypass Filtration System, filter changes are quick, clean and easy. This system also increases an engine's motor oil capacity, helping it work better, not harder.

➪ AMSOIL also carries Powersports Oil Filters, Engine Air Filters, Cabin Air Filters, Fuel Filters, Transmission Filters, Coolant Filters, and more...

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