How often do you change oil.

[Marekaofholland]

During the 40 odd years I change (currently a Perkins M90 from 1994) every year regardless the amount of hours. Every 5 years I send some oil to the lab for an oilanalyses to check on the state of the engine.
So far never a problem. Knock on wood....

[Newfoundgal]

I have been using the same oil for over 10 years! My engine is not very particular about the brand.

[Wolfy]

If in doubt, change it out......including filter.
Oil is cheap, engines aren't.

[RLMM]

100 hours would be the equivalent of 5000 miles on your car at 50 MPH.

[Allan S]

Once a year, or every 100 hours. Perkins 4-107.

[wallandj]

Oil and filter change once a year, always in the Fall - that way she goes into winter storage with nice sweet oil coating all the internals. If I put more than 200 hrs on her I might consider more frequent changes, but I never have exceeded 100 hrs annually.

[Bluechart]

When cruising, I’ll go longer between changes 150-200 hrs (manual says 250 hrs)
When “home” (San Francisco Bay) change annually or 100 hrs.

And, I change my transmission oil at the same time as engine oil.

Fuel filters 200-250 hrs.

[IanTrail]

I change mine as part of my winter laying-up programme. I have read that used diesel engine oil can be quite corrosive so I would rather leave my engine sitting in clean oil all winter. (Dockhead above says that this may just be superstition these days but, hey I'm a sailor; aren't I supposed to be superstitious?)

[Rasselas36]

3GM every 100 hours

[Sea Wolf]

We were on a 50’ catamaran with 2 Diesel engines. Depends on what you’re doing. As a general rule, every 100 hours or 3 months, whichever came first. It also depends on what your doing... things like heat, cold, and how the engine is run (loafing or pressing) also factor into the equation

[MAJICDAN]

I have a 1974 Perkins 6.354.
I use Amsoil HD marine 15-40
I sent in oil samples when I switched to Amsoil about fifteen or twenty years ago
I normally travel about 6000 miles a year.
I now change my oil every 600 hours.
I still change my oil filter every 200 hours.

[captainbri]

Changing oil is the best maintenance you can do, you can't change it to often Imho. I've only used 100% synthetic Oil.

I've never had to buy or rebuild an engine.

[Sequoyah]

100 hours or spring or fall, whichever comes first (i.e. twice a year or more if usage is high).

[Linesledaft]

I might be crazy, but I change my engine oil between 50-100 hours, check it before every start. I change trans oil about every 100, and it gets checked regularly too. Yanmar 3gm30f with a Kanzaki. I run the engine pretty hard sometimes and for me it is just good insurance.

[timb7734]

Also depends on the oil you use. If you use cheap oil, then change often and about 100 hours. I owned a truck fleet for 50 years, and approaches to lubrications changed over the years to the point that, with modern engines, we were at 20,000 mile drains on 15 liter diesels, without internal failures out to 500,000 miles. We used a formula of 45 mph implied, and controlled idling with electronics. The implication was then about 450 hours per change and over 11,000 hour minimum life until we traded up.. we used a good medium price oil which is Shell Rotella 15W40.

What do I do in my boats? Both are modern diesels, which get the 15W40 Rotella at 200 hours on mains and 100 hours on gen set. Try getting some Rotella in your hands, it cannot be wiped off without something to break it down. Some may consider changing every year is cheap “insurance” but it is unnecessary and even wasteful if you use good oil that has not been contaminated by fuel or coolant. I sample at least once per year. Additionally the additive packages in Rotella 15W40 are designed for on road operations where the emissions systems are dumping more combustion by products into the oil instead of the air. Fortunately that hasn’t hit boating as yet.

Conversely were I maintaining a 40 year old Perkins or Lehman I would be changing twice a year or at 100 hours.