Just saw a question/answer on Dec Motorcycle Consumer News. If you already knew this, feel free to ignore this. I haven't seen this and I thought it's educational. No, I'm not Chris. Not sure if he's on this forum.
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Oil Pressure and Filter Types Several years back, I remember reading an oil filter test in some publication or another. One of the highest rated filters to come out of that was the Purolator PureOne. I’ve been using them ever since on my ’08 FJR. However, on a recent foray into the Purolator website, I came across a warning on their powersports page saying specifically not to use the PureOne filters on bikes. They say that bike oil pumps generally aren’t up to the pressure needed for their extremely efficient PureOnes. They recommend using their bike-specific filters, the ML series. Any thoughts on this? I thoroughly trust your judgment on all things “bikish.”
Chris Goodfellow
San Francisco, CA
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Extremely efficient is one thing, but restrictive is another. Your FJR’s oil pressure relief valve is set to open at 75 psi. Will it ever see that much and spill oil back to the sump? Maybe, if the oil is high viscosity and cool. Absolute minimum hot oil pressure for your FJR is 4.35 lbs. at 1000 rpm. Will it ever actually go that low? Likely not, unless you have a badly worn engine or allow the oil level to drop very low. With exceptions, most modern bikes have warm oil pressure in the range of 30 to 50 psi at 3000 rpm, very similar to automobiles. So, what determines how much pressure is required to cause oil to flow through the filtering medium in a filter? Less than you might think. Oil filters contain (again, with exceptions) a device known as a pressure differential valve. This is not the same thing as the pressure relief valve at the pump which regulates maximum system pressure. The differential valve in the filter is set to open, regardless of pump output pressure, if pressure on the outside of the filtering medium exceeds the pressure inside the medium by some fixed amount. Otherwise, both flow rate and pressure would suffer downstream of the filter. That fixed amount differs, depending on the system the filter is designed for, but it’s generally on the order of 4 to 10 lbs. If the differential valve should open due to a clogged filter or very viscous, cold oil, some of the oil will be diverted around the filtering medium and delivered to the engine unfiltered until the differential falls back within range. If the company in question says that “extremely efficient” requires higher pressure, then I suspect the filtering medium is more restrictive and would require a higher differential pressure relief setting to avoid filter bypass under normal conditions. By recommending against the use of PureOne filters in bikes, maybe they’re erring on the side of safety, and I wouldn’t blame them. But my hunch is the recommendation has at least as much to do with promoting the sales of motorcycle-specific products. In either case, I’d take their advice and not use their PureOne filters on a bike. Go for the ML series, if you like. But there are many good brands of oil filters to choose from, both bike-specific and not, including Yamaha-branded filters.
—Stu Oltman
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Oil Pressure and Filter Types Several years back, I remember reading an oil filter test in some publication or another. One of the highest rated filters to come out of that was the Purolator PureOne. I’ve been using them ever since on my ’08 FJR. However, on a recent foray into the Purolator website, I came across a warning on their powersports page saying specifically not to use the PureOne filters on bikes. They say that bike oil pumps generally aren’t up to the pressure needed for their extremely efficient PureOnes. They recommend using their bike-specific filters, the ML series. Any thoughts on this? I thoroughly trust your judgment on all things “bikish.”
Chris Goodfellow
San Francisco, CA
--------------------------------------
Extremely efficient is one thing, but restrictive is another. Your FJR’s oil pressure relief valve is set to open at 75 psi. Will it ever see that much and spill oil back to the sump? Maybe, if the oil is high viscosity and cool. Absolute minimum hot oil pressure for your FJR is 4.35 lbs. at 1000 rpm. Will it ever actually go that low? Likely not, unless you have a badly worn engine or allow the oil level to drop very low. With exceptions, most modern bikes have warm oil pressure in the range of 30 to 50 psi at 3000 rpm, very similar to automobiles. So, what determines how much pressure is required to cause oil to flow through the filtering medium in a filter? Less than you might think. Oil filters contain (again, with exceptions) a device known as a pressure differential valve. This is not the same thing as the pressure relief valve at the pump which regulates maximum system pressure. The differential valve in the filter is set to open, regardless of pump output pressure, if pressure on the outside of the filtering medium exceeds the pressure inside the medium by some fixed amount. Otherwise, both flow rate and pressure would suffer downstream of the filter. That fixed amount differs, depending on the system the filter is designed for, but it’s generally on the order of 4 to 10 lbs. If the differential valve should open due to a clogged filter or very viscous, cold oil, some of the oil will be diverted around the filtering medium and delivered to the engine unfiltered until the differential falls back within range. If the company in question says that “extremely efficient” requires higher pressure, then I suspect the filtering medium is more restrictive and would require a higher differential pressure relief setting to avoid filter bypass under normal conditions. By recommending against the use of PureOne filters in bikes, maybe they’re erring on the side of safety, and I wouldn’t blame them. But my hunch is the recommendation has at least as much to do with promoting the sales of motorcycle-specific products. In either case, I’d take their advice and not use their PureOne filters on a bike. Go for the ML series, if you like. But there are many good brands of oil filters to choose from, both bike-specific and not, including Yamaha-branded filters.
—Stu Oltman
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