Oil changes - how frequent?

[Russell]

How often do you change your engine oil, especially those with Cummins engines? The manual says 500 hours or 6 months. This may fit a commercial user but for recreational use it makes little sense. 500 hours is way too long and 6 months seems too short as I would have less than 100 hours by then. I'm thinking once per year should do it.

[DougSea]

I had mine changed when the boat was hauled last winter and I'm planning on the same for this season. If I had gotten out more I've had considered another change at 100 hours but, since I didn't, it will just be the one change for this year.

If you're only doing it once a year I know the change before layup is recommended as you won't have the acids that build up in the oil sitting in one spot as the motor quietly spends the winter under wraps...

[JackK]

100 hours and or end of season. Like Doug. I change it prior to lay-up regardless of the interval before the next 100 hr. mark. Mine is a Yanmar engine.

Jack

[Pitou]

How often do you change your engine oil, especially those with Cummins engines?

Not sure which Cummins you have. I am powered with the 370 turbo 6BTA
and my manual says an Oil and Filter change should be done every 300 hours or 12 months which ever occurs first. With a six month season I don't come close to the 300 hour mark and perform this service at lay-up.

The manual also recommends the same for Fuel Filter changes, but these I always carry a spare just in case. Coming in this past Monday at WOT (3000 rpm) I was only pushing 17.5 knots. I shut down and changed the Racor filter and presto back to 27.3 knots where I should be. I usually cruise at 2200-2400 rpm and 18.5 - 20 knots. I blame this early filter change on a fuel stop I made a couple of weeks ago when I had fueled a half tank at a spot I don't usually go to. And after the fact, lesson learned, asked the attendant what filters they use on their pumps and he replied "we don't, you have a Racor and one on the engine don't you?"

[Denis]

I have the Peninsular and the manual reccomends 100 hours. I change it at the end of the season with about 70 hours per season. Fuel and trans. in the spring.

[Mariner]

Spring and Fall, or every 100 hours if needed.