Shell RTS 5w-40 vs. SAE 30wt for gas engines?

[Crusader]

This last year I've noticed several poster and one mod here that really rave about SAE 30 wt. Ok what can SAE 30 do better than RTS? I believe RTS will be slightly thicker at full operating temp however doesn't the 5w of the RTS provide far superior start up protection? Besides RTS turns in some solid UOA results? I did a search on this issue and found no direct results.