Originally Posted By: ledslinger
Originally Posted By: Donald
Originally Posted By: friendly_jacek
What is the benefit of using this vs leaving the engine dry?
There can be pockets of water you are unaware of. The better choice is Sierra or Zerex Low Tox. Either one mixed 50/50 with plain water does not cost much more than the pink stuff you can get at Walmart which you cannot dilute. Or get some antifreeze made for boat engine winterizing at a marine store. Use the pink stuff for your FW system.
I also prefer to fill the block with AF via pouring it in rather than to pull in the antifreeze running the engine. If you do it that way you are dependent on knowing when the thermostat is open.
But the pink stuff is better than nothing.
I agree with draining and pouring in the A/F, but many do suck it into the water pump pickup and have no problems. I've never seen a manufacturers' winterize instructions that sucked A/F into a running engine.
One of the problems with sucking into a running engine, as noted with your thermostat point, is unknown concentration of A/F. All winterize instruction I have ever seen leaves the exhaust manifolds of raw water cooled engines dry.
The only boat I winterize by sucking A/F into while running I drain the water first. It is a 50 foot Fountain express cruiser with 3 440 horse Yanmars. I did the winterize on it yesterday.
On something like a Mercruiser, you need to run the engine on water from a garden hose then switch to the antifreeze when the thermostat is fully open, then just before the last of the antifreeze is running in, you fog the engine and stall it. Too much to coordinate for me.