This sounds ridiculous, but I swear there's something to it. Recently changed oil to Shell Rottella T, with the 1515 exploder filter. I dropped the pan, cleaned pick-up screen (minor debris), peeped the sleeves, then blasted all the sht off with green brakekleen (california baby seal safe). Next day my wife said it felt like it had way more power. I hopped in and took it to town and felt a noticeable increase (unlike with the K&N filter). I don't think it's a nitrous effect because I let it drip for an hour before replacing pan.