IF you want to follow the book, change it every 5k miles. If you wnat to optomize your oil useage, send a sample in to
this lab and they will test your oil and tell you everything that is taking place inside your engine based on your driving habits and style. They may very well tell you that you can get more than 5k miles on an oil change. I have done this and since it take over 4 gallons to change oil in my 6.0 PSD, an extra 1000 miles is $$ in my pocket.
Last edited by Clay Henry : 07-26-2006 at 08:13 AM.