[Richard]

As an engineer, the motto is “In God we trust, everybody else bring data”. Meaning that no representative of a antifreeze company or Aquahot is going to tell you that it is OK to mix the products because they do not know what additive packages that may be in the mix. They do not have data on the unknown mix in your unit.

All the boiler fluid and antifreeze is ethylene glycol. Mix it and it’s still ethylene glycol. However, different companies use different additive packages to prevent corrosion and sedimentation. The reason that you are cautioned to avoid mixing is that two incompatible additive packages is that mixing them may cause them to precipitate and cause sediment in the system.