I NEVER thought I would say this but I am beginning to think, that maybe, there might be a difference between Amsoil and the competition.
I put Amsoil in our new rv, '07psd 6.0 and at drain time there still was a great deal of color left in the oil, granted I only left it in for 3.5k (I can hear some of you now, but I HAVE to do this, besides its only twice a year and the chasis is at nearly max gvw).
The fall change was with my beloved Del 1, have been using this exclusively since '99, and with only about 1k miles there is a very slight use of oil, very slight but the important thing is that with Amsoil there was not a molecule used.
Going back to Amsoil, signed up with the preferred customer plan so the product will be alot cheaper, even with shipping, plus I am going with a by pass filter and maybe a pre luber, of course I will be using their filters also.
Give it a try and decide for yourself.