There has never ever been even 1 single failure of a catalytic converter due to ZDDP ever recorded in the history of mankind. Theoretically the zinc and phosphorus CAN contaminate the platinum and palladium in cats and result in early car failure, but for that to occur you need to burn off enough oil with a high enough ZDDP content to poison the cat. Simply based on that possibility the EPA mandated lower ZDDP levels. Ironically though, the lower ZDDP levels means oils today could suck hard, resulting in more engine wear, resulting in more oil burn off and may even result in more cat contamination. Think about it, there are cars out there with over 100 or 200 thousand miles on them that ran high ZDDP levels for years and still do, and they still smog with 0 emissions, and have never had a cat failure.