The Neptune site was primarily concerned with the inclusion of PTFE (nanoFlon by Shamrock Technologies) in the formula due to the problems seen when a crude form of PTFE was used in Slick 50. The PTFE in nanoFlon is in the form of colloids 0.3-1.0 microns in size. They are permanently suspended in the oil due to the attraction these colloids have to the molecules in the liquid lubricants. The person who conducted the Neptune study did not completely deny that PTFE might work in the oil but was still uncomfortable "risking" his engine by using the SynLube.
When a proper form of PTFE is properly blended with the oil, there will be no problem with its use.
In regard to the viscosity of SynLube, 5W50, the problem here is that such a wide range of viscosity arouses suspicion since cheap polymers added to increase the viscosity range of an oil can fail under hard use and then the oil experiences "viscosity breakdown", a term coined by Castrol and which might very well apply to their 5W50 Syntec oil as some indications on the Redline Oil site seemed to suggest. SynLube, in contrast, stays "in grade" for the duration of its service life.
To date, I am unaware of any standards organization that has specifically warned or implemented standards contrary to the SynLube formulation. The 1996 formula met the new ILSAC and API standards without modification.
No one on the site except myself has even seen a bottle of SynLube, I have been using it for 4 years and have nothing but praise for its performance.