Pointed down is 6 o' clock, unless you use a 24 hour analog clock.

My bike came with slime-filled tires. They've never been able to stop a leak from even the tiniest pinholes. I've never had slime in my valves since I was careful to pump with the valve up top, but I threw the tubes away. All the slime ever did for me was to leak out where the hole was and make a huge mess that I had to clean up and made it difficult to patch the tire. It did make it easy to FIND the hole, I guess.