Please explain new motor oils to me

[85Bowtie]

I am reading all kinds of articles about premature wear on flat tappet cams because of the lack of zinc and phospherous in new motor oils.

I always thought that if you have a motor oil like Castrol GTX 20w-50 that doesn't say "Energy Conserving" on the back, it means it still has the zinc and phospherous. Is this true? Because on the 5w-30 and 10w-30 they do say "Energy Conserving".

Can you use Castrol GTX 20w-50 and not worry about a zddp additive on your flat tappet cammed engine?

Also, what about Rotella Shell 15w-40?

I don't want to ruin the cams in my vehicles but if you listen to everything you read it sunds like it's already ruined.

What's a good additive available off the shelf?

Thanks