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Friday, March 28, 2014

A Sheep in Oil Filters' clothing

    The oil filter is another place where myth seems to rule and fact goes floating by unnoticed. In a world of quick-in, quick-out, fast-food-style oil changes, the quality of the oil and filter are overlooked routinely.  Good oil filters can drastically increase engine life, crap filters can ruin your engine quickly.  I have seen low-cost filters actually come apart and ruin an engine immediately after an oil change, I have seen cheap filters whose back-flow valve does not work properly so the oil and dirt drain back out of the filter and pump, and I have dealt with filters that simply do not filter- they leave crud to circulate through the engine unchecked.
  The good filters cost more, plain and simple, and that may, by itself, be the deciding factor for the uninitiated.  For those in the know, using good oil and filters is natural, because with proper service, good lubricants can double or even triple the life of a machine.
    Two things any filter must have are lots of flow or volume of fluid (air, oil, fuel) through it, and the ability to trap & hold small particles indefinitely.  Have you ever been vacuuming your living room and noticed that the vacuum cleaner is leaving stuff behind and not 'vacuuming' properly?  Simple you say- the filter bag is clogged, change it out.   When your vacuum bag clogs, it is preventing flow because all of the tiny holes in the filter are filled with dirt or dust.  Imagine that same filter bag had larger holes in it- it would allow more dust back into the room you are trying to clean right?  Or how about if the holes are so small that they clog immediately and stop all flow through it? What if when you turned off the vacuum, the dirt all fell back out onto the floor? 
    These same considerations all come into play with oil filters, fuel filters and the intake air filters as well.  An engine needs a good flow of oil to keep it lubricated, but it has to be clean oil or that dust, dirt and chunks of metal in the oil will simply grind up our much loved machine.  So a good filter must flow lots of oil through it, have small enough holes to catch tiny particles, and have enough of those openings to allow lots of flow.  The secret is in the filter media -a loose pleated gauze in most cases- that allows oil to flow through it at high rates, yet extracts most of the particles and keeps them safely trapped. If the filter clogs, there is a bypass valve that opens and allows the unfiltered oil to flow to the engine. Getting the filter changed out before it can clog and open the bypass valve is very important.
    Another point to ponder: a cheap filter will have a cheap back-flow valve that will drain the oil- and dirt- back into the oilpan after the engine is shut down, only to be picked up by the pump again at next start while starving the bearings for oil due to absence of oil in the pump/ filter.  Compare this to a filter that costs few dollars more and most likely incorporates a better design that keeps the filter and pump full of oil and ready to pump to the bearings as soon as the engine begins turning. A good quality filter traps more fine dirt and holds it firmly while having a large enough surface area to allow oil flow through the filter media after its 3000 miles of particle collection have passed.
    The metal frame and can of a good oil filter is thicker and stronger than its cheaper counterpart as well.  The pressure differential between input and output sides of the filter can collapse the inner support core or explode the outer can on cheaper oil filters.  Rubber used in the sealing ring can be substantially softer or harder, stretchier or more brittle depending on brand, as can the rubber of the back-flow and bypass valves.
    Automotive engineers!! You are found out! Anyone who cares to can tell by the placement and orientation of the oil filter on an engine whether the engineers designed that engine for replacement, or for maintenance.  On my Cummins diesel, the filter screws  on straight up from below, and remains full of oil during installation.  On my parents Jeep 4.0l, the filter screws on down from above and empties itself as you screw it on.  Which engine gets oil starved after changing oil?  Which engine was built with planned obsolescence and replacement in mind?  To assist with Jeeps poor design, I wet the filter media to help eliminate air bubbles and speed flow-through, but cannot fill it much at all.  The more oil you can get into the filter that won't run back out when you screw it on, the better.
    Another thought- the oil pump sees the oil first with all the particulate matter in it from the bottom of the engine, before the oil filter.  The oil pump is the first thing to wear out in a lot of engines and it slowly takes the rest of the engine with it because oil flow and pressure continue dropping from early on in the engines life.  This is why I also advocate more oil changes during new engine break-in than most folks do. By removing the metal flakes and dust more often, this helps preserve the oil pump for later in the engines life.  Longevity starts from the first start, and how a machine is treated during its new years determines how long and how well it will last.

    So in my experience a few extra dollars spent on good oil change products usually results in engines that last many more miles. 
Right! Back to it, stuff to do.  Thanks again!

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