Testimonials are proof. They are not quantifiable proof, but meaningful proof nevertheless. Testimonials are a customers' word of mouth. I find customer word of mouth statements more credible than a vendor's in-house measurements or claims. Quantifiable proof requires an engine teardown. Which is exactly what ARX is purchased to avoid.
Many testimonials have posted photographs, which while not measurable proof, are evidence of results. Some are more compelling than others.
I have no doubt that the product doesn't work in all cases. It will not clean up a clean engine. It will not repair mechanical damage. I have had it not work in some instances.
I have used the product for a number of years. I try not to use it unless there is a problem. About 75% of the time I get discernible results. I most recently used it to save a colleague's S80 that had reached a low oil pressure warning from heavy sludging. The light was off within 200 miles of an ARX treatment, and significant deposits have been observed in subsequent filter cartridges. And the car is running substantially better according to the owner: most notably higher mileage. If someone wants to pay for a Volvo I-6 teardown to measure results, send the money. But for under $50, the S80 owner is very happy with the results.
M1 is a very fine oil. It keeps engines very clean. Some varieties, such as D1, are still best-in-breed. But looking at the OP, and the title of this thread, claiming M1 a better cleanser than ARX (and deriding ARX to do so), is rank boosterism. Perhaps Frank should wander over to the PCMO section and trash a certain variety of M1 that quickly thins way out of grade and then meets test sequence by oxidizing up? Is that what BITOG has come to? Tear down someone else to promote your favorite?
I have never seen M1 remedy a poor shifting ATX. I have seen a Ford AXOD full of M1 self-destruct. And I have seen ARX remedy a troubled ATX, more than once.
