I have used Delo 15W40 for about 15 years in everything I own that has an engine. This includes: Diesel MB's, Gas MB's, Cummins 6BT, Ford Diesel tractors, Toyota gas, Ford pickup gas, '88 Vette, Cub Cadet lawn mower, Dixon lawn mower and anything else that requires oil in crankcase.
I have had ZERO catalytic converter issues during that time. I think that the cat issue is an old wives tale otherwise it would not have the latest spark ratings. The engines that I've taken apart have been very clean inside.
I feel quite sure that the other quality Universal grades such as Delvac and Rotella T would perform in the same way.