The OP did not answer my question as to whether he knew how to use a search
engine.

Googling "rubber protectant" brings up over one million responses. Here's
one...

http://www.autogeek.net/lexol-rubber-protectant.html

By the way, the thing that protects a lens is a called a lens hood or lens
shade. Other than generic models, they are no longer made of rubber.

Why would I google when I have experts here to answer first.
Then I google to see if you know what you are talking about. Þ

Suggesting to Google is a cop out. :|