I've argued that the group III, group IV deal is blown way out of line by Castrol haters, so I'm not going wild on this.
I dumped half a bottle in with my 5w30 ST dino change and will try to get a UOA. ST and Valvoline are blamed for having weak additive packs, but they both seem to do fine in the real world.
Why don't you run some out to 6000 miles and do a UOA. There's too much Mobil 1, Amsoil and Redline in the analysis section-- I'd like to see people do a wider variety of brands.
As far as the quality of their additives, I thought most additives came from a handful of suppliers. If they're using group IV, you can bet that they're not doing that either. Warren is simply a blending and distribution house.
Look at the wide variety of people who have more than 150K on cars with low end dino. oils. This isn't rocket science....well maybe it is...