I agree with Elizabeth. Though I can't comment on the advisability of applying silicone to the surrounds, it is a bad idea to apply petroleum-based products unless you can ascertain the exact composition of the surround - not all "rubber" surrounds are created equal.
Some like to rotate their woofers occasionally, to counteract potential suspension sag. From everything I've read and encountered, it takes many years for a good suspension to suffer that phenomenon.
One of the best things you can do to prolong woofer life is to keep the grills installed, at least when not listening. Many speakers are voiced for use with the grills intact anyhow. In fact, 4 of my 6 pairs are voiced that way and sound better with the grills in place.
Some like to rotate their woofers occasionally, to counteract potential suspension sag. From everything I've read and encountered, it takes many years for a good suspension to suffer that phenomenon.
One of the best things you can do to prolong woofer life is to keep the grills installed, at least when not listening. Many speakers are voiced for use with the grills intact anyhow. In fact, 4 of my 6 pairs are voiced that way and sound better with the grills in place.