Jason,
Looks like the current list on the Amsoil is $26 a gallon, with some discount if you buy a case of four.
No doubt it's good oil, but the numbers don't work for me. I'm in exactly the same place as you: a truck that gets an annual change at 6-7K. I use the same oil in two farm tractors as well as the truck. I've done several used oil analysis using 15w40 R-T and the tractors and truck have come through very well with annual changes. I'm switching the truck and one tractor to the 10w30 R-T and will UOA them as well to get a baseline and see how that oil holds up. I'm also using the 10w30 in a couple of big riding mowers, so it simplifies my supply. I'm afraid to go witht he lighter oil on the big tractor because it has a ton of hours and gets worked very, very hard. When it works. I doesn't have to start in cold weather, so I'll keep it on 15w40.
I have a lot of respect for Amsoil products and have used (and still use) some of their products. Still, I figure a good UOA is a good UOA, whether I'm using $8.45/gal Shell or $26/gallon Amsoil and it leaves me more of my paychecks to spend on other things. If I felt the equipment needed it, I go with the Amsoil in a heatbeat. I've had the truck 20 years now with no problems, so with a good used oil analysis, I guess I can safely say the R-T has worked at least OK for me, huh?