On one of my prior 4Runner's I had the filter changed and there was some nasty black stuff coming out of it. I wasn't having any problems with the truck but it seemed like a good maintenance thing to do. I wouldn't do it too often but I think it needs to be done to keep the fuel injection running properly. My current 4Runner has 148K miles on it and I'm not sure if the original owner changed it or not. I need to check his records, he was good with the maintenance and I'm grateful.