Just wondering what sca stands for and what does it do?

 

Supplemental Coolant Additive. It saves your engine. If you do your own search on "Diesel cavitation", you'll get a much more scientific (and probably more accurate) description, but in a nutshell - diesels run at such high compression that the coolant in the coolant jackets on the "other side of the wall" from the combustion chambers can actually form some sort of bubbles along the jacket walls. Those can eventually cause minute pitting of the block wall. Left unchecked, it can eat all thee way through to the combustion chamber. New engine time. The SCA somehow interferes with that process chemically within the coolant. But that interference consumes a tiny amount of the SCA every time, which is why you need to add more periodically to keep the anti-cavitation level up.