Found this here,
http://www.xs4all.nl/~chris/slick50.html
"The problem with putting PTFE in your oil, as explained to us by several industry experts, is that PTFE is a solid. The additive makers claim this solid "coats" the moving parts in an engine (though that is far from being scientifically proven). Slick 50 is currently [1994] both the most aggressive advertiser and the most popular seller, with claims of over 14 million treatments sold. However, such solids seem even more inclined to coat non-moving parts, like oil passages and filters. After all, if it can build up under the pressures and friction exerted on a cylinder wall, then it stands to reason it should build up even better in places with low pressures and virtually no friction.
This conclusion seems to be borne out by tests on oil additives containing PTFE conducted by the NASA Lewis Research Center, which said in their report, "In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant."
Remember, PTFE in oil additives is a suspended solid. Now think about why you have an oil filter on your engine. To remove suspended solids, right? Right. Therefore it would seem to follow that if your oil filter is doing its job, it will collect as much of the PTFE as possible, as quickly as possible. This can result in a clogged oil filter and decreased oil pressure throughout your engine.