My wife's cream puff S70 (less than 36k miles), developed a nasty steering rack leak recently. It is leaking from the passenger side rack boot. I've called around and gotten several ~$1,000 quotes to replace the rack. We've been using Lucas Stop Leak and it has slowed the leak buying us some time, but is not a solution.

First question is what would cause the rack to die such an early death?

Another observation -- some days it barely leaks at all and other days it gushes. Doesn't seem to have any correlation to how much she drove it that day. Could it be related to outside temperatures? With Spring approaching temperatures can range from 30F to 70F degrees day to day here in Colorado.