Always check the owners 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 the following conditions:
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 that 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 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 (By-Pass) 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 by-pass, valve is used to allow unfiltered oil to lubricate the engine. Unfiltered oil is far better than no oil at all. This relief (by-pass) valve is built into the engine block in some cars. Otherwise, the relief (by-pass) 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 (by-pass) 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 insures that there will be a continuous supply of oil available to the turbocharger and the engine’s lubrication system upon start-up.
Note On Dry Starts: If a vehicle has not been operated for several days or after the oil and filter is 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.
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 Multi-Pass 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 above mentioned methods interprets efficiency from a different point of view. A brief explanation of each follows.