I have a 2000 460 with Cummins 6CTA8. This boat is new to me in July of this year and has been in fresh water all its life. Because of the remote location of Lake Powell it is not the most user friendly to have a really good Cummins service tech on hand or close by. I have a Tech coming " 150 miles away" to the boat to do the 600 hour valve lash adjustment. Also recommended is the coolant flush and replace. My question to the members that know whats best is this. As the boat has been in fresh water all its life do you think "flushing" is still needed to be done or would you just replace the coolant. The boat is on the hard and getting the bottom done and I dont have water access to run the motors while it is on blocks. My thought was while the Tech is there do I get the punch list done or should I wait until back in the water and just do the flushing with the coolant change. Also do you lose and coolant when changing the zincs? Thank you you for the advice.