Yup ..... no leakage.
Yup, no water leaks. PTFE is one of the lowest frictional materials known. The lower the frictional properties, the less heat generated. Traditional flax packing has to be constantly cooled by the small flow (drips) of water; not so with PTFE (if you compress it properly in the packing gland). The GFO is 100% PFTE unlike some of the flax packings that are 'impregnated' with PTFE or some of the 'paste' type PTFE 'mixtures'. If you change from standard packing, I'd recommend that you remove/pull the shaft and visually inspect for corrosion, surface irregularities, galling, etc. ... and if present you may need to have the shaft 'dressed' in a machine shop (or replaced). GFO, like any packing, needs a *smooth* shaft surface.