Perf-form Filters—high performance oil filters for motorcycles

PERF-FORM manufacture replacement oil filters for the entire line-up of Harley-Davidson models as well as all popular brands of motorcycles on the market.

All Perf-form oil filters incorporate leading edge technology with the use of a microglass/synthetic enhanced filtration media. Technical reports state that glass enhanced filter media has an increased efficiency for particle retention in the 4—22 micron range, the particle size most effective in reducing engine wear. Glass enhanced media also provides the added benefit of higher levels of dirt holding capacity without increased flow restriction or back pressure.


Electron microscope at 50 times magnification illustrates the fine particle-catching fibres woven into the microglass enhanced media used in Perf-form filters. This new technology filter media is considerably more costly than standard cellulose media used in other filters, however the improved filtration translates into longer engine life.

Perf-form 2

50 times magnification of the cellulose media used in cheaper filters clearly shows the lack of finer fibres woven in.

The number one filter in the Perf-form line-up was originally known as the HD-1 but more recently going under the new # OF-0012. This filter drops directly into the oil tanks of all big twins from 1965 through to 1981. The same filter is used in K models, 1953 to 1956 (except some competition models), and all XL models (except XLCH and XLC). It replaces the messy original equipment cup and retainer system with a simple one piece drop-in unit.

The original equipment in-tank oil filter as first used on the K model, then XL’s and FL’s. The OF-0012 is a direct replacement for this setup.

The first model Harley to use spin-on filters was the FXR introduced in 1980 with rubber-mounted engine and five-speed transmission. This was the first big twins since 1965 to depart from the oil tank with the drop-in filter. The OF-0016 black (Genuine #63805-80A) and OF-0018 chrome is a direct replacement for this filter and will fit all rubber-mount engine models, Softails, 1991 and later Sturgis, 1984 and later Sportsters, and 1999 to present Twin Cams.

OF-0026 (Genuine # 63810-80 ) is a short spin-on filter also available in chrome (OF-0028) used on Sportster models from 1979—1983, FL models 1982—1986, and some FX models. It is the only filter in the line-up with a 5/8 x tpi mounting thread.

Now also offered is a filter introduced for S&S engines. The filter is designated the OF-0037 (black) and OF-0038 (chrome). Dimensionally the same as the OF-0020; it is a versatile filter and will also fit Twin Cams.


Perf-form # OF-0032 is an extra long black filter (also available in chrome under # OF-0034) specifically for Dyna models. At 5.53 inches long it is the longest filter in the Perf-form family and fits all Dynas from 1990 through to 1998.

Harley-Davidson V-Rods and Buells are also well catered for with state-of-the-art Perf-form filters readily available. These filters are only offered in black at this stage.

The black Perf-form filter for the Buell has its own metric 20 x 1.5 thread unlike the ¾ x 16 tpi on most of the other filters.


Perf-form also manufacture a handsome filter/cooler with a replaceable element, the HD-CXS (OF-0042). The filter/cooler mounts directly to any ¾ inch x 16 thread spin-on filter mount. It provides oil cooling with fast economical filter changes for late model Harley-Davidsons with front mount spin-on filter. The HD-CXS comes with a chrome plated finned aluminium canister housing, stainless steel nut plate and port nut, all the necessary seals, three replacement filter cartridges, and a socket filter wrench for mounting and cartridge replacement.

Perf-form oil filters are manufactured in the USA and imported and distributed throughout Australia by Redgrave Motorcycles (02-9484-9900) and Pro Accessories Australia (07-3277-0693). For any technical information, feel free to give the guys at Redgraves a call. Dealer enquiries always welcome.

Thank you to Pedro at Harley City for his help in sharpening up some of the fitment dates on the Big Twin models and Lewis ‘K’ Mcewan for confirming some of the K model dates that absolutely nobody else knows.

Why We Have Filters

MOTOR OIL has a number of big jobs: lubricating, cooling, sealing, and absorbing contaminants. Some contaminants go into suspension and some are chemically grabbed by the additives, which constitute up to one-fourth of an oil’s makeup. Acting by itself, oil would soon become saturated with contaminants and allow the internal parts of an engine to wear. That’s why we have filters.

Early automotive engines didn’t use oil filtration which was okay if the engine burned or leaked enough oil during normal operation that almost constant replenishment with new oil compensated for any accumulated dirt.

The development of pressure lubrication brought about a need for some type of filtration to protect the oil pump from damage and excessive wear. At first only simple wire screens were used in the oil pump intake. These were reusable after cleaning, usually in kerosene.

Ernest Sweetland invented the modern oil filter in 1923. He named the new product Purolator, a combination of the words Pure Oil Later. The new oil filter was incorporated into the lubricating system after the oil pump and before the oil flowed into pressure lubricated bearings of the engine.

The early oil filters used on cars were low performance and not really effective. Many successful and popular engine designs (VW, Fiat) did not use any oil filters until the 1970’s. Some engines used oil filters ONLY in by-pass and not in main flow of pressurised oil.

As engines got tighter, higher revving, and oil stayed in longer, filtration became a must.

Most oil filters look simple but they’re the subject of continuing research and development to make them work better. Physically, oil filters resemble a metal can that houses varying types of filter ‘media’. These are the materials that capture organic or inorganic contaminants as oil flows through. Organic contaminants include bacteria and other organisms that form sludge. Inorganic contaminants consist of dust that’s ingested into the engine, along with trace amounts of wear metals from bearings and other internal parts.

The filter media materials have changed over the years. Early designs used steel wool, wire meshes, metal screens, etc. Later bulk cotton or various woven fabrics like linen were used. When disposable filters became popular, cellulose and papers were used to minimise production costs. Finally synthetic media oil filters were introduced where special man-made fibres are utilised. Today, most low-cost disposable spin-on oil filters use cellulose filter media. Better quality oil filters use synthetic media, while top end oil filters use microglass or extremely fine metal mesh.

How The Filter Works

THE oil enters the oil filter under pressure through the holes on the perimeter of the base plate. The ‘dirty’ oil then passes through the filter media where it is cleaned. It then flows to the central tube and back into the engine through the threaded hollow center mounting stud.

Most filter medias can only pull out particles as small as 25 to 30 microns (a human hair is 67 microns in diameters) without restricting oil flow. Microglass technology solves the problem by using special synthetic glass microfibers that are about 10 times smaller than conventional cellulose filter fibers and still allow full flow. Research has shown the following performance:

Harley filters are called “full-flow” because 100% of the engine oil passes through them in normal operation. The filters must work without introducing a lot of restriction or else oil will not flow into the engine during cold start-ups. They are designed to cleanse the oil during normal service and this assumes the oil is changed at the recommended intervals.

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