An industrial-strength, glycol-based inhibitor package, HDIS-1 inhibits corrosion, enhances performance and produces outstanding propylene glycol and ethylene glycol heat transfer fluids. Fluids made with HDIS-1 are versatile and long-lasting in even the most demanding applications. They can be used effectively in cooling systems for the large, stationary diesel engines used to drive natural gas compressors; in line heaters and bath heaters used to keep natural gas above its hydrate formation temperature; in engine generator sets for electrical power production; combustion air preheaters; and industrial diesel engines. HDIS-1 contains no silicates, but has an outstanding non-silicate aluminum corrosion protection system. It contains no nitrates or amines. HDIS-1 protects against cavitation erosion/corrosion in wet-piston-sleeve diesel engines.