"Roger Long" wrote in message
...
I abused my engine the same way for the first two seasons because I heard
(probably here) that you just change the oil in a sailboat engine at the
beginning and end of each season. I felt rather foolish as a former flying
club maintenance officer who used to track operating hours and maintenance
intervals compulsively. We did oil analysis and it is all about trends.
It won't tell you much unless you either graph the numbers or can visualize
graphs in your head. It is changes from the norm you are looking for and
you need the experienced advice from the analysis company unless you know a
lot more about engines than you appear to or even than I do now after
reviewing the reports for nearly a decade.

I woke up when I noticed that engine manual says to change the oil every
50 hours. Same interval as my old airplane BTW which makes sense because
both are hard working engines. High pressures in the diesel and lots of
blow by in the airplane due to being air cooled. Gallon per hour average
consumption in cruise, 20 gallon tank, the oil should be changed after
every 2 1/2 fill ups if you use most of the fuel before going to the fuel
dock as I do. I round it to three fuelings to account for convienience
and to account for idling and slow legs in the harbor.

Since even a small amount of operation puts some acids into the oil, it
should be changed every 2 - 3 months even if you are not motoring that
much. If you are a tank a seasons sailor, I would still change mid season.
Oil is cheap, even at today's prices, and engines are expensive. If you
are using that little fuel, you may also not be operating enough to boil
some of the water and acids out of the oil.

In reference to the other long thread about filling tanks, I run my tanks
down as close to empty as possible so that I use up as much of the old
fuel as possible and have the maximum proportion of fresh fuel in the tank
after filling. That's a more common recommendation among the mechanics
and engine people I've talked to around here. I never heard of topping
off to avoid water in the fuel in boats until I read it here. Buying near
tank fulls of fuel makes it easy to keep track of oil changes (no engine
hour meter on my little engine). I could buy and add on but there's that
complexity thing

--
Roger Long

Roger, I could easily change it every few months... it's not hard at all.
Besides, I have plenty of oil-absorbant pads. The marina gives them away for
free.

--
"j" ganz @@
www.sailnow.com