Engines that need SCA are modern engines made light by exposing the cylinder walls to the coolant.
Old style engines where the cylinders are pressed into sleeves in the block do not need it.
Under load the cylinder walls expand and contract with each power stroke. When the cylinder shrinks back to size it is very rapid, so fast that a vacuum is formed on the outer wall surface , which is the cavitation that eventually could eat right thru the cylinder.
Evert big truck stop will sell the SCA and the measuring cards used to confirm the proper mix.