I have a marine 1977 Perkins T6.354 6 cyl, 6 liter turbo diesel. There are different types of coolant available and I've done significant research into this question and have not found a clear answer.
Most of the diesel information available pertains to modern wet sleeve diesels and they recommend the modern D-6210 spec, which come in different flavors (HOAT, OAT, NOAT). These formulations have improvements around corrosion and pitting over "traditional coolant" that is D-3306 spec.
All the antifreeze at the parts shop are D-3306, with one bottle of 6210.
This is a dry sleeve engine with probably an old head gasket. My concern is the newer 6210 may not be compatible with it. The original spec in the manual recommended an outdated formulation that is no longer available.
Should I use D-6210 or D-3306?