Does car wax ever go bad?

I found a giant bottle of Zymol that I bought about 10 years ago. My first thought was "SCORE!"

But does this stuff ever go bad?

It does break down, I'd shoot Zymol a note and see what they say about your 10 year old wax find. ;)

I would use it. If its too thick its water soluble so you can add a little water to soften it up.

Usually it separates out over time. Otherwise use it with your soap in the wash bucket. Read the directions about how water sets it in the finish.