1993 Johnson Evinrude "ET" 90 degrees CV Service Manual, P/N 508285, Page 92Get this manual
Spark Plug Information The spark plugs should be removed and examinedA spark plug should be replaced if the electrodes are badly worn, if it has cracked insulator, or is badly fouled Before installing the spark plug cover on the spark plug, apply light coating of OMC Triple-Guard grease to the ribbed portion of the spark plug ceramic and to the opening of the spark plug coverThis will help prevent corrosion of the spring terminal on the spark plug which can cause high tension arcing