I run nothing but Amsoil. If you use the 100% synthetic, you can go 25K without changing the oil.
I too was skeptical, but I've run Amsoil in my 03 Suburban since it was new, and I can tell you that I avg 18 to 20 mpg hwy with the ac on doing 70. The engine now has 130k and sounds like day 1. I also run amsoil in my 02 V-Star..no problems.
Yes, a quart of Amsoil will cost you about double what a quart of dino oil will cost, but if you look at it from the standpoint that you can go 25k..let's do the math
5 quarts Amsoil $35 + (2) filters @ $7 = $49 Good for 25K miles
5 quarts Dino $17 + filter @ $7 = $24 good for 5 to 7K miles, now multiply that by 3.5 times based on that fact that is how many times your going to need to change your oil to reach 25K, and your running your dino oil to 7K, your total amount spent would be $84
Now lets take that $84 minus $49, the cost for the Amsoil, and that leaves us with a savings of $35
So I ask....how are you saving money, let alone your time by going with Dino oil? Ok you may say whoa...25K on oil...don't believe me, send in a oil sample, that is what I did at first, it came back with flying colors.
My .02
Steve