Coolant flushing- Coolant change - Replacing engines zincs

I would just replace it personally. Make sure you order the correct coolant filter without SCA's so you don't have too much additive. In addition, replace the thermostats when you flush the coolant and clean the heat exchangers and aftercoolers. This way you only have to make the mess once. So this is what I would do.

1. Remove the aftercoolers and heat exchangers.
2. Service them both per SBmar.com
3. replace them on the boat.
4. Change the thermostats.
5. Change the coolant filter.
6. replace the coolant hoses
7. refill the boat with coolant, don't forget to dump and replace the coolant on the overflow bottles.
8. you will need to top off the coolant in the spring when you splash it and can run the engines so make a very large note of this somewhere.

9. Drink some Beer... no 2 beers... drink 12 beers and wait for summer.

You do not lose coolant when changing the zincs... they are on the raw water side.

No need to have the tech do it, then you have to do it again when you perform the other maintenance items. I hate changing the impellers on my engines, I would make the tech do that!
Josh