Condoms and oil-based lubricants

It’s been drilled into our heads for 20 years not to use oil-based lubricants with latex condoms because oil causes the latex to break down. My questions are how quickly does that breakdown occur and is there a particular concentration of oil that’s required to start that process?

Well, maybe you should note this:

New condoms (such as Avanti or Trojan Supra) are made out of plastic (polyurethane) and can stand up to an oil-based lubricant. They are stronger and thinner than latex, and are non-porous and non-permeable to viruses including HIV*. They warm to the body’s temperature unlike latex and are hypoallergenic (important if you are allergic to latex).

http://www.sexualecstasy.org/facts-myths.php

I had a college roommate who discovered that it didn’t take very much oil-based lubricant at all and that the condom was finished before he was.

Sufficiantly that you shouldn’t roll on a condom with hands that are oily something totally innoccent like cooking or a massage. What I have always understood is one greasy thumbprint is enough to end up with a burst or un-noticibly holed condom.