Can I add too much RMI-25 to my Antifreeze?

Engines that operate in conditions where surrounding temperatures are likely to approach or fall below freezing point must use antifreeze in the cooling system to prevent the cooling system fluid from freezing over.

The main element in antifreeze lowers the freezing point of the water-based liquid. Various concentrations of antifreeze in the cooling system allow for a wide temperature range to be tolerated by the engine coolant, from usual freezing temperature i.e. 32°F (0°C)  to  −34 °F (−37 °C).

Once antifreeze has been mixed with water and put into use, it periodically needs to be maintained. Part of the maintenance process is to check the ‘freeze point” of the antifreeze mixture. In the event of engine cooling system fluid loss, or if the cooling system needs to be drained and refilled, the antifreeze’s freeze protection should be checked and adjusted if necessary.

If RMI-25 is added from time to time to ensure that the correct pH level of the cooling system is maintained, the freeze point of the antifreeze may be affected by the dilution. If this could be an issue, it is recommended to check the freeze point during routine maintenance procedures of the engine. Should it be necessary to correct the freeze point, remove or drain some of the cooling system fluid and add antifreeze to restore the desired freeze point.

Freeze point can be tested with a refractometer or a special bubble tester.