Auto paint sealants work by filling in the pores of the surface, and providing a slick surface that defies bugs, dirt and the elements. Or, so you would hope. Some are better than others and the following is simply from experience.

I had a new Mustang GT professionally "protected" with Auto Armor back in 1985. About three months later, I made the huge mistake of parking under the pine trees at my sisters' campsite, and the next day my car was covered with sticky sap from the trees. I didn't know what to do except try washing it off with cool water and then see what I needed to do. It was like a miracle; all the sap on the paint slid off easily with nothing left behind! Then the big chore was cleaning the windows, but the paint was spotless! The protectant worked, at least in the short term.  Three months later I drove to the West Coast and ran through a cloud of insects in Florida. I had an insect screen on the car, and although I tried to wash them off as soon as possible and also drove through rain for several days, the front of the vehicle was permanently pock marked with their body acids or whatever from then on.  I followed instructions and "renewed" the sealant every 6 months with the provided "renewer". The vehicle was garaged every night and about 40% of days, yet after 4 years I noted fading in the charcoal paint. The renewer really didn't keep the finish quite as slick as the original and I was disappointed that the protectant didn't protect against the insect damage. So, In short I guess the hundreds of dollars in sealant cost did protect against the tree sap but was not of great value in the long run.

A second Mustang GT in 1987 had a sealant named TST applied by a shop that the dealer sends cars to. Unfortunately, the bozos who did the job buffed off the clearcoat and I had a dull car with a sealant on top. When you wiped your hand or a rag over the hood, the paint came off! The choice was to repaint the car or simply continue to apply sealant regularly. Another sealant job gone bad! Then I found they hired kids to do the work and gave them almost no training in the use of buffers. The owner said it could be applied by hand but would take too long and the kids would miss half the car. Hmmm...for four hundred bucks you would think they could apply it with a Q-Tip!

Teflon is kind of a misnomer. Look at your chemistry books and see the temperature that is required for teflon or PTFE to bond with metal. About 800 degrees fahrenheit! At that temperature you wouldn't have paint on the surface! You don't see many teflon products around anymore to lubricate your engine because it just doesn't simply bond with metal surfaces like that. There are polishes and waxes containing teflon but I can't say they have proven to be any better than ordinary waxes in protecting my cars. Again. personal experience only.

I presently use Griot's Garage Paint Sealant on vehicles that have to be outside a lot. First I wash the car and then clay it to remove all contaminants. Then apply the sealer as directed. Apply every 6 months or so and the finish is great. On a black car it's a shiny as any other wax or finish I have ever used, no degradation in finish from air contaminants, easy to wash off. And, Griot's doesn't say it contains teflon or anything else. They sell it as a paint sealer and it seems to do just that.

Enjoy your cars and be safe.