Every 100 hours is correct (or every year at winterize if not 100 hours).
Use straight 30 weight oil (not 10w or 5w or etc).

--
Tony
my boats and autos - http://t.thomas.home.mchsi.com


"Richard Malcolm" wrote in message
om...
How often do people change their oil. I have an 1993 OMC (ford) King
Cobra I/O. I have been changing the oil about every 100 hours. Just
read somewhere that 300 hours is OK? What weight would you use up in
New England for this time of the year. I generally will pull my boat
out for the season in late December.