I'm going throw this out there. So i just pass my 2nd year of using amsoil. I change it once year or 20,000 miles and change the filter every 6 months or 10,000 miles. Sooo after two years i have 100,000 miles on the truck and the engine is still doing good. I'm getting 18-20 mpg depending on how i drive for the week. Now i just change the oil and going on to the 3rd year. Here's to a good 3rd year.
I'm not trying to say go buy amsoil, i'm just saving alot of time and money. Sure up front it cost alot to buy the oil,but i'm saving in the end.