Supplemental coolant additives (SCA's) are a chemical package added to coolant either as a liquid, powder or charge inside a filter to fortify the coolant’s anti-corrosive and other desirable properties. Note: OAT extended life coolant does not require SCA's but should always be topped up with OAT Premix. ES Compleat should be topped up with ES Compleat Premix or DCA4 to replenish additive level if required.