Can anyone tell me what synthetic is “thickest”? I.E. highest range on the 30 side?
Judging by your Korean models in your Signature and probably needing SN Plus ....
Quaker State Ultimate
Rotella Gas & Truck
Google both for data sheets.
However, Thickest is not Bestest. If it were, both of my Korean vehicles would be using ^^those-2^^
In mid-priced ($23-$35) 5w30s I like - in no particular order....
Pennzoil Ultra Platinum
Valvoline Modern Engine
Castrol Edge EP
Mag-1 Synthetic (I found at NAPA)
It's my Fine-As-Wine 9.
..... without the need to take a loan-out, for five quarts of TGDI / GDI oil.