I've never heard of any detrimental effect regarding catalytic converters associated with ANY oil. If the engine is using so much oil that it is burned to a point of damaging a catalytic converter, that car is suffering many more problems than oil can cure or cause.

I use Chevron Delo 15W40 in everything from lawn mower to 300E. The only exception is Mobil One in my new C Class.

The 300E now has 244,500 miles and still requires no oil to be added between changes. The additional detergents in these universal grade oils are GREAT for gas engines, cat or not.

Have a great day,