By-Pass Valve Myths

We have seen the statement many times that a by-pass valve is required for safe engine operation. However, testing has shown us that by-pass valves do more harm than good. A by-pass valve is a device that allows oil to flow thought the filter without flowing through the filtering element. The original purpose of the by-pass value was to keep oil flowing if the filter medium became so plugged with contaminations that it starved the engine of vital lubricant.

The operation of the by-pass value is pretty simple. When the pressure on the upstream side of the filter medium is markedly greater than the pressure on the down stream side of the filter medium, the valve opens and allows oil to flow unfiltered.

Our studies of oil filters have shown that there are no standard values for the pressure difference required to operate the by-pass value. We found that 86% of our studied filters had leaky by-pass valves and allowed oil to flow unfiltered at all times. So these filters do little to actually protect your engine. Further more, there were also a small percentage of filters that had by-pass valves that failed to open at all. The paper filter medium in these filters eventually failed and broke up into large pieces of paper which plugged the oil return holes in the filter base. Had these filters been installed on a vehicle instead of our test stand, the engines would have suffered catastrophic failure. For those filters were the by-pass valve did work properly, the filter emptied most of its debris contents back into the engine. So almost all of the harmful particles that had been filtered from the oil were now returned to the engine in a big rush as the layers of contaminates broke loose from the filter medium and entered the oil stream once again. The end result is the same as running the engine without a filter at all.

It should also be noted that a filter should never become plugged when proper maintenance is being regularly performed. So the only way a filter should become so plugged that a by-pass valve is needed is if the engine has a catastrophic failure and large debris from the failed component flows into the filter. If that occurs the engine is toast any way.

So why is Trufilter different? Our product is designed to allow frequent cleaning and inspection of the filter’s internal components. If regular inspections are made, you can see debris from failing components and do further inspections of the engine to locate the failing component before catastrophic failure occur. Also, with regular inspections and cleaning of the filter you can gain a much better understanding of the condition of your engine. A by-pass valve provides no real benefit and does more harm than good. So we left it out of our initial product line as our goal was to provide the best filtration possible and extend engine and lubricant life.  That’s why Trufilter is the best Filter you will ever purchase for you vehicle.