How often do you change oil.

[MicHughV]

It's moot....you can't compare a gasoline car engine to a diesel engine in a boat.....two entirely different mechanical propulsion systems. A car engine gets used daily, most diesels remain idle for weeks on end. Let's face it, most sailboat engines can sit weeks at a time without use.

Car engines operate at relatively high rpm...marine diesels rarely see 2,500 rpm..

diesels operate at very high compression ratio's, car engines ....relatively low rpm.
car engines go up and down the rpm range...marine diesels generally are brought up to a certain rpm and stay there all day long.

The science of oil viscosity is too long to enumerate here.

I can go on and on...but why...???

Most diesel manufacturer's recommend 100 hr oil changes...just like most car manufacturer's suggest 3,000 miles between changes.
It's partly business talk....ie, get you to come in and spend money on something you possible don't need. It doesn't hurt to change your car oil every 3,000 miles, so why bother to argue the fact.
Same with diesels. It doesn't hurt to change every 100 hours, so why bother to argue the fact.

The only important difference is this. In a car, mechanical assistance is never far away. Service stations are on every street corner. You can buy oil at any 7-11 store.

On a boat, things are different. 99.9% of the time, the oil change interval is up to you, the owner. You may not be near a service place. Your only oil availability is what you carry onboard. Your diesel engine is pretty much "entirely" dependent on you, the boat owner, for service and maintenance. There are no " Jiffy Lube" places available for boats. There are no convenient 7-11 stores either, especially true, when underway.

Keeping this in mind, changing oil at 100 hours is a prudent decision. It may not be required, but then again, why not. Your life may depend on that engine one day, why not be judicious in deciding when to change oil.....that's really all there is to it !!

The 100 hours is not a mandate, it's a "recommended" interval based on above. If you change at 125 hours due to circumstances, it is also ok, it's not the end of the world.

Marine diesel, by their very nature are extremely robust and by and large, require little beyond clean fuel and clean oil to operate forever.

That's all you gotta do, provide clean oil and fuel, and that engine will respond by giving you a life of service.

Seems a fair exchange to my way of thinking.

[rslifkin]

If running a lot of hours, it's likely worth sending an oil sample for analysis a few times to determine an appropriate change interval for your chosen oil, engine and usage pattern. Some combinations will chew up the oil in 100 hours, others will be fine to go 500. There's no one size fits all rule.

[Simi 60]

Originally Posted by carstendenmark

!

It's a mess to change oil and filters, EVERY time ! Don't deny it.

Doing "boat-yoga" (thanks, Dan), the smell, and the dirty oil (both Diesel and black old engine oil) to clean up.
Yikes !

Depends on the boat and the engine

We have full standing headroom in the ER
There are no smells and the oil at 250 hours is clear enough to read the marks on the dipstick through the oil.

37 litres of old oil is pumped directly into the containers it came in, no mess, no effort.

[Linesledaft]

Originally Posted by Simi 60

Depends on the boat and the engine

We have full standing headroom in the ER
There are no smells and the oil at 250 hours is clear enough to read the marks on the dipstick through the oil.

37 litres of old oil is pumped directly into the containers it came in, no mess, no effort.

GD wish I hd that. No mess on ours either though.

[Boaster]

I think changing oil every 2 years is fine unless you are constantly using the engines.

[rslifkin]

Changes on mine are pretty low mess as well. Take the vacuum extractor down to the engine room. Suck the oil out of 2 engines and the generator, change filters on 2 engines (generator doesn't have one), pour in new oil. No fussing with drain plugs or pans. And the oil filters on the engines are remote mounted over the exhaust manifolds and they're vertical, so minimal mess when removing them. I have considered moving the filters up higher to make it easier to get a container under to catch drips, but it's not bad as-is.

[Poldhu]

Originally Posted by BonesD

Curious what others do.

In my case I might have 30 hours on last years oil & filter change
The oil looks great. Engine is 40 year old Perkins 4-236.

Do I change it just because it’s been a year?

How many hours do you go on an oil change?
I’m sure there are lots of “what if’s and it all depends on ” concerning this question.
Just looking for generic answers.
Thanks

At the end of the season regardless of use. New filters, new impeller, new synthetic 10W40 Shell T6 Rotella. Cheap peace of mind.