That's the theory but I don't subscribe to it. For one thing you need
to make sure the thermostat is open and that's hard to do idling in the
drive. The merc cooling system thermostat bypasses the block when
closed and the incoming raw water goes straight to the exhaust
manifolds.

The only thing I use the pink stuff for is our jetski. The boat I
drain the block, manifolds, and the power steering cooler and leave the
plugs out till spring.

D&LBusch wrote:
Do I need to drain the block and hoses if I'm using one of those coolant
kits that attaches to the muffs on the outdrive? It would appear not.
since it is sucking in the Anti Freeze and will displace any water left in
the block. Thanks in advance. David