The info, references, in the above posts make sense, Kirk. It's obvious that Synlube is doing a good job keeping your engine(s) clean. You are using products in your various machines that represent a lot of money. I'm certain that if you suspected that you were doing any harm to your various machines, you would stop using Synlube in a heartbeat. Your record keeping is very systematic and accurate. I'm not buying into the "viscosity issue." How many random samples were tested? How many different labs did the testing over how many samples? I may be wrong, but one or two samples tested by one or two labs may not be very very meaningful. I put more weight on your on-going, long-term "successful" usage. Tearing down those various pieces of machinery would be meaningful, too, but whose got the time and money for such extensive tests?