Yamaha 60 Owner's Manual page 46

Operation
prevent them from becoming clogged with
salt deposits.
NOTE:
For cooling system flushing instructions, see
page 43.
Cruising in turbid water
Yamaha strongly recommends that you use
the optional chromium-plated water pump kit
(not available for some models) if you use
the outboard motor in turbid (muddy) water
conditions.
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