After all, the engine has its own brains - a controller, its own nervous system - electrics, the heart - cylinders, blood - motor oil. There are not only reproductive organs, but it’s a pity … But the engine has its own liver, that is, an organ that serves to cleanse the body: a kind of dump, garbage! This is an oil filter. And, fortunately, it can and should be changed with every oil change - the engine "cirrhosis of the liver" is useless!
The choice is huge: imported and ours, small and large, expensive and cheap … For our new examination of the "eight-decimal" VAZ filters, we easily bought 24 types of these products in Moscow stores - two of each type. The tests were carried out at the Department of ICE of the St. Petersburg State Polytechnic University.
We raised the topic of the “cleaning manager” more than once - we measured the filtering surface area, evaluated the nominal screening fineness … But if all the previous examinations were based on the guest test procedure, now it's time to compare how the filters work in real conditions, that is, directly on engine as part of a lubrication system. For this we have never taken!
WITHOUT PAPER YOU …
What did we check and how?
To begin with, we satisfy curiosity: what is inside? It’s not by chance that we took two filters each … To do this, carefully, on a lathe, we cut off the bottom, pull out the “offal” and admire them. Well, the case is one piece, the valves are two pieces (bypass and return), the filter element is also one. True, there is the “Super Filter Kolan”, where there are even two, but this is exotic.
The design of the filter element is relatively small - usually a cartridge filled with corrugated filter paper. The filtration area is very important, since it largely determines the filter resource. Interestingly, this area from filter to filter changes more than two and a half times. For example, at the "Champion" it is more than 1300 cm2, while at the "Citron" it only slightly exceeds 500 cm2. The number of corrugations varies from 54 to 85 - even for filters of similar sizes. In some, the corrugation step is uniform, in others it is somewhere empty, and somewhere so thick that you cannot even find a gap between the corrugations. It would seem - well, okay, does the area not change? Haha: try blowing a single sheet of paper and then a stack of it. Why does this oil go the way of the greatest resistance, where the corrugations simply formed? So it turns out that the real, active filtration area depends on the quality and uniformity of the corrugation. And that says a lot about production technology. It goes without saying that in the final assessment we will certainly take into account the quality of the paper structure.
From paper to valves: bypass and return. The task of the first is to track the moment of critical filter contamination and prevent the engine from dying from oil drought: dirty oil is better than none. It works according to the elementary principle: when the filter becomes dirty, the pressure in front of it increases, and after it drops. The valve opens and part of the oil passes uncleaned, but the pressure behind the filter, that is, in the oil system, increases.
And here is the question: what should be the effort to open the bypass valve? There are filters - for example, Tsitron Raider, where an increased opening force is claimed as a distinctive property. Say, at peak pressures on a cold start, the valve does not let dirty oil into the engine. But is it good - how can it be without oil? On the other hand, this effort should not be small - otherwise dirty oil will immediately rush into the engine. So what is right? There is no official answer to this, so we took the average value across the sample as the norm.
With a check valve, everything is simpler. Its task is to keep the oil in the filter while the engine is stationary. The less oil in the housing, the longer the oil pressure lamp does not go out during startup - not good! We evaluated the quality of his work by the loss of oil for a fixed time, starting from the same condition of the engine. That is, the engine was stopped, and after 30 minutes they were measured - and how much oil is left in the filter?
And now - the most interesting. In standard tests, the filtering ability is evaluated at special facilities, and the oil is contaminated with special dust. But everything is not so in the engine! Firstly, dust should filter the air filter, and oil mainly works on wear products, that is, on metals. Secondly, a real filter works under conditions of significantly variable oil pressures and temperatures. And this, obviously, should affect the quality of oil cleaning. And most of all we need to know how different filters will behave on the same engine, the same oil - and how will this affect the engine itself? Feel the difference?
The tests were carried out on a VAZ 2108 3 engine mounted on a load device that allows you to work in any mode - from idle to "nominal". Of course, the “motor wrapping” program was identical for all filters. Oil is also from “one barrel”, and not even allegorically. And as those wear products, we used a strictly dosed amount of aluminum powder - an analogue of real wear products, using the engine flushing procedure that was previously tested in advance. It is also fundamental that we checked the filtration quality under real operating conditions of the engine! The viscosity of the oil and its pumpability through the porous structure of the paper also depend on temperature! And the quality of filtration was evaluated by spectral analysis of samples of contaminated oil …
By the way, how do various filters affect the oil pressure in the engine lubrication system? As far as we know, no one has ever received this information! Instead of an oil pressure sensor, we inserted an accurate laboratory pressure gauge, and put a thermocouple in the pan to take measurements at exactly the same oil temperature. Looking ahead, we note that, depending on the filter, the difference in pressure, for example, at 4000 rpm, was as much as 0.7 atm between the best and worst samples, that is 25%! This picture was preserved in other modes. It turns out that the oil system does not notice the best filters for this parameter (Sintech, AC Delco), although the filtration quality remains quite normal, but the worst ones, such as Olefant, are like a blood clot! And this is fraught with "hypertension" for the entire engine.
In general, welcome to the final table. We chose weights based on the importance of the parameter: the first thing is the ability to clean, the last is the appearance and operation of the valves. Study, please!
NOT ALL FILTERS ARE EQUALLY USEFUL!
Standards are standards, not all filters are the same! After all, you will not begin to recommend, for example, Citron, which effectively extinguishes pressure in the oil system, against an old Vazik, which will live to see its overhaul, it is already not easy for him. And with a low viscosity of oil in the summer it is also undesirable to use it. You may not kill the engine, but the flashing oil pressure light will be very annoying.