When should Walkers SST be reapplied?????

I have had it on my stereo for 3 years and I could hear a difference. How often should i clean and reapply?? Doesnt silver tarnish???
Silver oxide (tarnish) is still highly conductive, and one advantage of the SST is that when it dries it creates a tight seal on the connection. I don't think Lloyd Walker has ever suggested a time frame for cleaning and reapplying, and I can't tell you based on my system because I've never had something unchanged for that long a period. (After one 12 month period, I couldn't tell that cleaning and reapplying made any difference.) If you do clean a set of connections, I'd be interested in your report on whether the cleaning and new application made a difference over the three year period.