playinthemud, I hope I haven't upset you in any way. I just have a passing interest in this issue where I have a lot of time on my hands over the holidays. I'm a chemist and I'm always interested in attempting to determine if these "miracle cures" have any merit for myself.
Like most Americans, I do not trust testimonials from Amsoil users and mechanics. Most of the articles I've read over the past few days were from Amsoil promoters, some were from individuals that rated Amsoil products very highly. All were very positive about Amsoil, except for its price.
I'm not sure what you meant by 100% synthetic oil, but Amsoil does use additives just like the big brand oil companies. Anyone looking at the Amsoil comparison test results with a little engineering, chemical or analytical experience would see that most of Amsoil's tests dealt with issues that were reliant on common engine oil additives. Knowing that only a small amount of each additive is necessary to meet API certification, big brand companies chemists probably only add what is necessary, and is probably dictated by auto manufacturers' own chemists and engineers.
The overall point is that the majority of Jeep engines do not require synthetic oils to keep the engines clean and performing well. Any modern multiweight non-synthetic (or, even durablend) motor oil recommended by the manufacturer is going to protect the engine well and keep it free of sludge as long as the manufacturer's oil change frequency is followed. What's more, is that Amsoil is too expensive for use in an offroad Jeep that will most likely see frequent engine oil changes; economics does not warrant such extravagance. Happy holidays, and have fun playing in the mud! <img src="/forums/images/graemlins/cheers.gif" alt="" />