I have a 2007 Dodge 2500 with the 5.9. Started using Amsoil at 15K miles. Now at 145K. Amsoil is PIA to get and it seems from reading the Rotella-T may be a good alternate. Any suggestions. Been running 15/40 year round.

 

Rotella 5-40 synthetic T6, just as good and way cheaper, I just did a oil change oil filter filter, fuel filter, (Baldwin, for under $100 bucks in my front yard, took 45 minutes, have used it since new, all good.I do mine twice a year.

 

Same here, I've been using Rotella T6 synthetic for the past 6 years with no problems, you can find it cheaper in Walmart together with Mopar oil filters. I change my oil twice a year, I drive my truck about 15k miles/year. I highly recommend this oil, much cheaper and excellent quality.