We are blending automotive and industrial lubricants in which we use virgin and recycled base oil. In recycle base oil there are suspended dust particles that we can't see with the naked eyes initially. In lines we are using PP filter bags for filtration of 10 - 25 microns before pump and the pump capacity is of 15 hp gear pump of 1440 RPM.(depends upon viscosity).(viscosity of oil ranges from 5 to 40 CST at 100 degrees centigrade, but the blending process is at room temp -- 30 degrees centigrade.) But after filtration and after a few days we can see with our eyes,brown or black dust particles settled in the bottom of the cans, or if we take the same oil in a 500 ml glass cyliders, we can observe the same after few days, and also after settling particles, oil becomes more clear and bright. I would like to ask you whether this problem can be solved by using 1 to 5 microns filter bags, as oil is difficult to pass through these bags or we use 20 to 25 hp motors so that oil can pass through it easily.