A rancher in Southern California has an interesting oil filter setup. He runs Delo 15w40 in most trucks and tractors on the ranch. When he changes oil he puts the used oil in a tank that has an outlet at the bottom which is 4 pipes. Into the pipe he stuffs rolls of toilet paper with the center plugged so that the oil has to flow through 12 rolls of toilet paper, in series of three, into a second clean tank below. He rotates the rolls, throws out the top roll which has the most gunk in it, puts a new roll on the bottom and starts filling the tank, again. The oil in the catch tank comes out really clear. It takes several days for the oil to work it's way to the catch tank and he processes the oil three or four times based lab work and also makes a decision on when to start over with new oil. He supports 22 vehicles with this system and his books show that he is not only saving money on oil but his tbo for his tractors has increased by almost 50% with his more frequent oil changes that he can now afford to do. He is also using the system for hydraulic fluid with good results, too. Anyhow I just though I'd post this to see if there might be any comments. His oil changes go pretty quickly, with a pump to empty the sump and another to fill it. The filters on the engines last longer now, too, and some of them are really expensive. This guy is a real rancher/engineer, some of his tractors are 40-50 years old and they do all the work at their on site shop/barn.