I read somewhere here about substituting mayo for sour cream. does it work? is it an equal substitution or do you need to do do a different amount of mayo to the amount of sour cream the recipe calls for?

yes yes and no

Edited real quick to say: omg I'm smoking crack--it's an equal parts substitution for oil. It might work for a sour cream sub but I don't know for sure.

http://www.cheapcooking.com/substitutions.htm

If you scroll down, it says that you can use sour cream as a sub for mayo. Hope that helps!