They use treated water, it looks green like anti-freeze, but it's just dyed to show that the water is treated. Sometimes you'll see purple too, but we usually see green. They drop a few tablets of this stuff into the overflow tank & it disolves. In EMD's it's almost impossible to keep coolant seepage out of the cranckase & into the oil. They will steam out the water, but if it has antifreeze in it, it attacts the bearing surfaces. When these engines cool down, in some cases, the cylinder liner can shrink away from the head, breaking the seal, and letting water drip down on top of the piston. An above post talked about opening the cyl. cocks on a cold start for this reason. I've seen a few that actually did squirt out a little water, but usually only a mist or a few drops. They say GE, which has a 4 cycle with a cast block & individual power assemblies, (instead of a fabricated 2 cycle) is a sealed engine, and can run antifreeze, same with the Cat 3600 series, but for uniformity, they are treated the same as EMD's. All of our locomotives have an auto drain feature that activates below a certain temp if the engine is dead for more than about 30 minutes. It trigggers a drain, and dumps all 250 gal or so of coolant, to prevent freeze up. Any fuel savings at shut down? Sure, between 5 & 8 gallons per hour idling.
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