For the purpose of this post, I will be talking about full flow filters. I will go into more depth in a later post about the different kinds of oil filters that are available. With that being said, a lot of the things I am going to talk about here will pretty much apply to any kind of filter.
To start off with, lets talk about microns. A micron is a particle that has a cross section that measures 0.000039 inches. To get an idea of what we are talking about when we mention microns, the cross section of a human hair is approximately 100 microns across. With that in mind, when we talk about the filtering capability of a filter, we need to know two things, the particle size, in microns, and the efficiency. For instance, the AMSOIL Ea Filters are 98.7 percent efficient at 20 microns. What this means is that 98.7 percent of all particles larger than 20 microns are stopped at the filter. So when some company tells you that their filters are rated at 20 microns, they are only giving you half of the story. You also need to know the percent efficiency at that micron size. Be wary of any company that does not mention the full story, or any of it for that matter. One has to wonder why they would not proudly display their rating.
Next time we will talk about the flow issue.