I think I have a new hobby now... thank god, cause the guitar hero was killing my hands!
Here's another one from our friends at TDS...
"if you are using Amsoil in your 6.0 I will be happy to inform you, I have oil samples of 6.0 engines that have oil samples with 22,000 miles and the oil was still good for continued use. the oil sample is your oil change reciept if you have any engine issues.
the dealer cant tell you a word on the subject.
I personally have run the 5w30 HDD over 40,000 miles without a change and have the oil sample to prove it.
dont let others that have no experience on the subject sway you with opinions.
Amsoil makes the best products on the market period."
on edit: quoting TDS