if your talking about things like "slime" I don't like that stuff anymore. Its messy and when you get a flat that it does not seal it is even a bigger mess.
For instance, to put air in a tire that has slime in it, you need to have the valve at the upper half of the rim, like between 9 and 3 or else when you hook up a pump, you get slimed.
after a while you will find slime in your pump or in your compressors air chuck
I have even had the slime not allow a shrader valve to close correctly after putting air in, letting the iar back out, then me having to fiddle with it only to pump it up again
I used to have slime in my main commuter but got tired of the mess
I then switched to Kevlar tires and even put in liners, only to get a puncture in the sidewall where the liners and Kevlar do not cover.
I now just run airstop ( thick tubes) and tires that have either Kevlar or the similar and don't ride my main commuter with half worn tires.