Other information:
Inspection
NOTE:
Dropped spark plugs should always be discarded.
Unfired
An unfired spark plug should appear very clean
with a pure nickel finish to the threads and ground strap. The center
electrode ceramic insulator surface is often a matte or dull finish and
pure white in color...
WARNING: Failure to follow engine
block heater instructions could result in
property damage or serious personal
injury.
WARNING: Do not use your heater
with ungrounded electrical systems or
two-pronged adapters. There is a risk of
electrical shock...