Antifreeze for the Hyundai Sonata
The Sonata is one of the most common Korean saloons in Georgia and often arrives as a hybrid. Valvoline Zerex Asian Blue is an approved formulation for Hyundai's MS591-08, one of the rare cases where the data sheet uses the word approved.
Photographs come from the manufacturer's official materials.
Cooling system volume (litres) roughly six to seven litres
The GDI engine and thermal load
The Sonata's Theta and Nu family engines are direct injection and made entirely of aluminium. Direct injection means higher temperatures in the cylinder head, and aluminium is a far more reactive metal than cast iron.
Two figures from the data sheet describe the aluminium protection: weight loss in the ASTM D1384 test is 0 mg where the limit allows up to 30 mg, and the repassivation result is +447 mV against a limit of −400 mV.
Repassivation means, in practice, that a damaged aluminium surface rebuilds its own protective film.
The Sonata Hybrid and its second circuit
The Sonata Hybrid has a separate cooling circuit for its power electronics. The same logic applies here as on Japanese hybrids: the passages are narrow and deposits show up immediately in heat transfer.
Valvoline Zerex Asian Blue measures under 10 ppm silicon, contains no borates, and carries a phosphate package that works against deposits and scale.
Still check the manual for the specification listed for each circuit, because some hybrids and electric vehicles have their own requirement.