HPL EC is a full formulated oil to be used in place of regular oil (about 1qt). They recommend 20% about 1qt. 1x EC with 5x qt oil.
It is not an add at the end of an OCI and then dump it. Many users here have used it for full OCI (myself being one). Just like VRP check filter at 2k and adjust for your usage conditions.
My sons Forte had 3 rounds of EC30 at full OCI ~5k miles. I have some pictures of what was in the filter canister after that 3rd one but I'm sending
@53' Stude the filter element to cut apart next week before I post those. I did post his top end valve train pictures which was about 1000 miles after and that was spotless. I don't know if from the EC30's or in general but the junk in filter is a lot.
His car is definitely quieter at start up (like piston slap noise) then what it was prior to HPL use. I ran out of EC30 so now use 1 qt of HPL PCMO 5W-30 with whatever oils I am using in three vehicles. We'll see what future filters look like.