I have an old sink spout, probably from the '80s. old aerator was deteriorating, installed new one (mail threaded) seems to turn tighter ok but after it's in it leaks a lot of water through the sides. Teflon doesn't work. I bought some pipe thread compound and thought if that didn't work I'd use silicone and let it dry for two days. I know the silicone alternative may prevent me from ever changing the aerator again but by that time I'll be ready to replace the whole faucet assembly or the sink itself. Pipe thread stuff says to apply only to male threads but I thought if it helped I'd apply to all threads. (Mail threads are relatively few as you can imagine how aerators are.) Any ideas?