Here are answers to questions we get all the time. Think of it as a little friendly advice from experts you can trust.

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  1. Where can I buy FRAM® filters?
  2. How often do I need to change my filters: oil, air, fuel, transmission?
  3. What can I do to find an obsolete number and if there is a cross-to a new number?
  4. What are the differences between Tough Guard®, Extra Guard® and Ultra Synthetic™ filters?
  5. What causes over-pressurization?
  6. What valves are in oil systems and are they in the oil filter?
  7. How are filters tested?

Where can I buy FRAM® filters?

See Where to Buy.



Always check the owner’s manual to determine when fluids and filters should be replaced. It is very important to note that there are different recommended change intervals depending on the type of driving you do.

The Severe Maintenance Schedule is described by these conditions:

  • Short trips of less than 5 miles.
  • Short trips of less than 10 miles when outside temperatures remain below freezing.
  • Towing a trailer or camper, using a roof-top carrier or carrying maximum loads.
  • Operating in severe dust conditions.
  • Stop-and-go driving.
  • Excessive idling.

If your driving habits frequently include any of these conditions, you should follow the Severe Maintenance Schedule.


What can I do to find an obsolete number and if there is a cross to a new number?

Call our catalog department at 1-800-890-2075, then press “2.”



Please refer to the Products page on our website for a description of each filter and its benefits.


What causes over-pressurization?

Over-Pressurized Filters: From time to time, a used oil filter will appear bulged or deformed. A bulged oil filter is one that has been subjected to too much pressure – a condition that occurs when the oil pressure regulating valve is malfunctioning. When a bulged oil filter is discovered, the pressure regulating valve should be serviced immediately.

What causes over-pressurization? Excessive engine oil pressure is the result of a faulty oil pressure regulating valve. To properly separate the engine parts and prevent excessive wear, the oil must be under pressure. The pump supplies oil at volumes and pressures greater than what the system requires to lubricate the bearings and other moving parts. The regulating valve opens to allow excess volume and pressure to be diverted.

There are two ways that the valve fails to operate correctly: either it sticks in the closed position, or it is slow to move to the open position after the engine has started. Unfortunately, a stuck valve can free itself after filter failure, leaving no evidence of any malfunction.

Note: Excessive oil pressure will cause filter deformation. If the regulating valve still remains stuck, the gasket between the filter and the base can blow out or the filter seam will open. The system will then lose all of its oil. To minimize the risk of an over-pressurized system, motorists should be advised to change the oil and filter often.



Oil Pressure Regulating Valve: The oil pump pressure regulating valve, usually built into the oil pump, helps control the operating pressure of the lubrication system. The regulating valve is set by the manufacturer to maintain the correct pressure. The valve utilizes a ball (or plunger) and spring mechanism. When the operating pressure is below the preset PSI level, the spring holds the ball in the closed position so oil flows to the bearings under pressure. When the desired amount of pressure is reached, the valve opens enough to maintain this pressure. Once the valve is open, the pressure remains fairly constant, with only small changes as the engine speed varies. If the oil pressure regulating valve becomes stuck in the closed position or is slow to move to the open position after the engine has started, the pressure in the system will exceed the regulating valve setting. This may cause an over-pressurized oil filter. If a deformed oil filter is observed, the oil pressure regulating valve must be serviced immediately.

Relief (Bypass) Valve: In a full-flow system, all of the oil passes through the filter to reach the engine. If the filter clogs, an alternative route to the engine must be provided for the oil, or the bearings and other internal parts may fail due to oil starvation. A relief, or bypass, valve is used to allow unfiltered oil to lubricate the engine. Unfiltered oil is far better than no oil at all. This relief (bypass) valve is built into the engine block in some cars. Otherwise, the relief (bypass) valve is a component of the oil filter itself. Under normal conditions, the valve remains closed. When there is sufficient contaminant in the oil filter to reach a preset level of pressure differential to oil flow (around 10-12 PSI in most passenger cars), pressure differential on the relief (bypass) valve causes it to open. This condition can occur when the oil filter has become clogged or when the weather is cold and the oil is thick and flows slowly.

Anti-Drainback Valve: Some oil filter mountings may allow oil to drain out of the filter through the oil pump when the engine is stopped. When the engine is next started, oil must refill the filter before full oil pressure reaches the engine. The anti-drainback valve, included in the filter when required, prevents oil from draining out of the filter. This anti-drainback valve is actually a rubber flap that covers the inside of the inlet holes of the filter. When the oil pump starts pumping oil, the pressure will unseat the flap. The purpose of this valve is to keep the oil filter filled at all times, so when the engine is started there will be an almost instantaneous supply of oil to the engine.

Anti-Siphon Valve: When a turbocharged engine is turned off, it is possible for the turbocharger’s lubrication circuit to siphon oil from the oil filter. To prevent this from happening, the turbocharged engine’s oil filter is equipped with a specially designed, one-way, shut-off called the anti-siphon valve. Oil pressure keeps this spring-loaded valve open while the engine is turned on. When the engine is turned off and oil pressure drops to zero, the anti-siphon valve automatically closes to prevent the back-flow of oil. This valve ensures that there will be a continuous supply of oil available to the turbocharger and the engine’s lubrication system upon startup.

Notes on dry starts: If a vehicle has not been operated for several days or after the oil and filter are changed, some oil may have drained from the filter in spite of the special valves. This is why it is always a good idea to start the engine slowly, letting it run on idle for 30-60 seconds, so the lubrication system will be fully charged with oil before a heavy load is placed on the engine.


How are filters tested?

Filter Engineering Measurements. Measuring efficiency must be based on the premise that the filter is present on the engine to remove harmful particles and thus protect the engine from wear. Filter efficiency is the measurement of the filter’s performance in preventing harmful particles from reaching the wearing surfaces of the engine. The most widely used methods of measurement are single pass efficiency, cumulative efficiency and multipass efficiency. The standards that specify how these tests are performed are written by world-wide engineering bodies: SAE (Society of Automotive Engineers), ISO (International Standards Organization) and NFPA (National Fluid Power Association). The standards to which FRAM filters are tested are the automotive industry’s accepted methods for evaluating and comparing filter performance. Each of these methods interprets efficiency from a different point of view. A brief explanation of each follows.

  1. Filter Capacity is measured in a test specified in SAE HS806. To create a successful filter, a balance must be found between high efficiency and long life. Neither a long-life filter with low efficiency nor a high-efficiency filter with short life is useful in the field. The contaminant-holding capacity as defined in SAE HS806 is the amount of contaminant removed and held by a filter from the oil during a constantly recirculating flow of contaminated oil. The test is terminated when a predetermined pressure drop across the filter is reached, typically at 8 psid. This pressure drop is associated with the setting of a filter bypass valve.
  2. Cumulative Efficiency is measured during the filter capacity test conducted to SAE standard HS806. The test is run by continuously adding test contaminant (dust) to the oil circulating through the filter. Efficiency is measured by comparing the weight of the contaminant left in the oil after the filter, to the known amount that has been added to the oil up to the time of analysis. This is a cumulative efficiency because the filter has many chances to remove the dirt from the oil as it is circulated repeatedly through the filter.
  3. Multipass Efficiency. This procedure is the most recently developed of the three and is carried as a recommended procedure by both international and U.S. standards organizations. It involves a newer test technology in that automatic particle counters are used for analysis instead of simply weighing the dirt. The advantage of this is that the particle removal performance of the filter can be found for different size particles throughout the filter’s life. The efficiency determined in this test method is an “instantaneous” efficiency, because the number of particles before and after the filter are counted at the same instant. These numbers are then compared to generate an efficiency measurement.
  4. Mechanical and Durability tests. Oil filters are also subjected to numerous tests to assure the integrity of the filter and its components during vehicle operating conditions. These tests include burst pressure, impulse fatigue, vibration, relief valve and anti-drainback valve operation and hot oil durability.
  5. Single Pass Efficiency is measured in a test specified by SAE HS806. In this test the filter gets only one chance to remove the contaminant from the oil. Any particles passed through the filter are trapped by an “absolute” filter for weighing analysis. This weight is compared to the amount originally added to the oil. This calculation determines the efficiency of the filter in removing particles of a known size, the size that caused the significant engine wear, 10 to 20 microns. The name single pass refers to the fact that the particles go through the filter only once instead of many times.