Long time listener, first time caller. I would like your expert opinion on this. I read an article in the 2013 July/August issue of Auto Service Professional where the author (who is Dan Pike, group executive of Filter Manufacturers Council) claims that cellulose based filter media is better than synthetic media because "cellulose media is better at adsorption and impingement, it can remove more contaminants than glass or synthetic media without plugging [filter] pore spaces". The thinking behind this claim is this: "The process of fluids and contaminants collecting on the fluffy fibers of cellulose fiter's surface is called adsorption. The more adsorption a media applies, the more small particles can be separated before they reach the small pore spaces on the screen side of the media." Now since "cellulose media typically is thicker than synthetic...particles spend [more time] traveling through it. Each time the fluid changes direction around a fiber, the momentum keep particles traveling in the same direction they were going and they are driven into the fibers. This particle separation is called impingement. As with adsorption, the more impingement that a media applies, the more particles are separated without plugging the tight pore spaces on the screen side". "Sythetic media does separate some particles with adsorption and impingement, but the smooth fibers can't hold the particles in place. Often they are washed off with the fluid traveling through the media. Synthetic media primarily uses the particle separation technique called direct interception. Direct interception is simply separating particles by passing the fluid though pore spaces that are small enough to catch them. Once all pores are filled with the contaminant, the filter is plugged and its life is over." Thus since cellulose media holds the particles better than synthetic media "it can remove more contaminants than glass or synthetic media without plugging [filter] pore spaces". For those that want to read the article at can be found here: http://asp.epubxp.com/i/148057 pages 50-58.