Hello Declan, Any Ethylene Glycol coolant that is compatible with aluminum will work. We recommend and use Shell Rotella ELC coolant in the U.S.A. It is phosphate free and silicate free and considered an extended life coolant. We still recommend changing it out every three to four years.
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Best regards,
Farron
Technical Sales and Service for Beta Marine, US Ltd. Minnesott Beach, NC PH: 252-249-2473 farron@betamarineusa.com