That also brings up another discussion. I currently change my oil every 4 to 5k and I drive on the freeway much more than I drive the streets, 45 minute commute one way to work, school is about 20. When I drove my dads truck a while back, he had me change it every 2k, he towed a lot so I'm guessing that's why. My buddy changes his trucks oil every 20k! It's shocking to me.but he's got 200k on his Harley ford 150 and he drives it very hard, lot of street racing. So how often do u guys change oil?