2006 Pajero Gen3 3.2 SWB Oil

[Optic]

hi all
i have done quite a bit of reading and after owning the vehicle for 2 weeks I want to replace all oils.
I have seen that most say Caltex Delo 400 MGX is the best......
I can only find Delo 400 SLK at our local parts shop
I see that MGX has a API rating of CJ-4 AND SLK is CK-4.
so in theory SLK should be a better oil because of the higher rating?
please educate me as I might be missing something

TIA