You can filter now or filter later. Most saws that depend on the blade bathed a bit in the oil have sufficient oil tank volume that the particles settle out in the bottom until the oil is totally contaminated (i.e. every morning my saw has a clear layer of oil above the sediment). Filter it often and you will be reducing particles to the cutting surface. Use a pump and settling system outside the saws tank and you can probably reduce sediment to the blade but it will involve a larger volume of oil (essentially the same as filtering more often). Me I use the criterion of when my oil is dirty enough to stiffen a bit, contaminate the window on my cover, or fail to show settling even after an overnight quiet period - then I filter. That batch filters and a new batch is reintroduced to the saw for continued cutting during the 2 week or so filtering process using the brown paper bag method. A pump is a luxury, but from my perspective it involves a complicating factor of being potentially harder to control the amount of oil delivered to the blade and hence misting. Its easy for me to determine how far into the oil my blade reaches, and hence how much oil it carries up to strike the rock being cut. Using a pump would involve a valve to control that flow. When I cut rhyolite or softer rocks I have to change my oil more often, but normally even with heavy cutting, I can go a month or more without an oil cleanup. Just my thoughts after using several types of saws.