My notes from my first coolant exercise, a couple of years ago:
- Normal antifreeze is 96% ethylene glycol, and 4% additives, used in a 50/50 mix (check label - some antifreeze is already pre-mixed)
Probably green, may be labelled "inorganic" or "conventional" (e.g., Prestone, Zertex)
- "OAT" is "organic acid technology"
Usually orange (e.g. DexCool)
- "Hybrid" = OAT plus the inhibitors from green
May come in many different colors
- RV antifreeze is propylene glycol plus inhibitors
Biodegradable, less toxic, often pink or purple
MaineSail says NOT to mix antifreeze types unless it says
safe for all makes. "if it is green stay with green" and DO NOT MIX"
If you don't know what was in there before it is best to
-- drain
-- fill with distilled water
-- run to temp
-- drain
-- (repeat 1-2 times), and then
-- fill with new antifreeze
I did the fill/flush thing a couple of times, and have been running Prestone 50/50 mix (green) ever since.
(says it is good for any vehicle and compatible with any color (type?) of coolant...)
BTW, as an aside, I asked the tech at the local Kubota dealer for "diesel coolant". He laughed and said "it's over there on the shelf next to the blinker fluid". He implied that "diesel coolant" is an urban myth. I don't know nuthin' (and I can generally prove it), all I can say is that the Kubota guy recommended "normal coolant in a 50/50 mix in a Kubota motor", which, after all, is what our Universal diesels are under the gold paint.
I've since been advised that there is actually a kind of coolant made for heavy-duty/high-compression/high-temp diesels, but that it's probably not needed in our relatively low-load boat-motors.
From Wikipedia
"Propylene glycol methyl ether is used as an antifreeze in diesel engines. It is more volatile than glycol."
$.02
Bruce