Engine Oil Change Frequency

[boeing1]

when I lived up north i changed the oil and filters before laying the boat up for the winter. now that I am in the south and use the boat more, I change every 6 months. might be over kill but is a very inexpensive oil change

[model 10]

[QUOTE=Dockhead;2428623]Well, it was designed that way by Yanmar.



I bet not, it would not be in their interest to do that. If for some reason they thought it was OK they would have you using 0-5wt oil. Modern oil likes to run at well over 200deg F. It takes most of that to burn off the water.

[Alan j]

The owners manual for my Kubota marinized by Phasor says 200 hours. A very experienced mechanic told me every 100. That seemed like a lot but I got to thinking if I averaged 30 mph in my car a hundred hours would be 3,000 miles which used to be the recommended oil change interval. Nowadays cars are designed to go 5k or even 7.5k between changes but fastidious owners might still do it ever 3k, so I decided every 100 hours was a reasonable interval for me.

[a64pilot]

Originally Posted by Dockhead

Is this realistic? Mine goes through a cooler and never seems to get warmer than lukewarm.

I change every 100 or every 6 months. Whichever comes first.

Zap the oil filter with an IR temp gun, I bet it's hotter than you think.
If not, then you need to run it harder to get it up to temp every so often. Piston aircraft should be run at 180F, idea is to get enough heat to cook off the moisture, as Guy said moisture combines with combustion products and creates acid, acid of course etches bearings etc.
The number TBN you get from oil analysis means Total Base Number, it's the ability of the oil to neutralize acid, oil needs to be changed when it loses this ability, unlikely modern oil ever breaks down if changed anywhere near recommended intervals. The acid build up is the reason for calendar limits on oil most likely.
Little Diesels like ours, primary reason to change oil is to remove the soot, it gets soot loaded and ought to be changed long before it breaks down, for this reason you won't get the benefits of Syn oil like say an old Turbo Porsche would. Soot is Carbon of course and carbon is abrasive.
Personally I change oil at 100 hrs, something I got from the Farm, see oil is at its best the day it comes out of the bottle, from that day on it degrades, your choice to say how far you let it before you change it.

[a64pilot]

Average modern automobile engine's oil temp runs above 200F, usually a little more than the coolant, a lot of performance cars run oil coolers that cool oil with engine coolant, the coolant is of course 195F, so oil has to be hotter than that to be cooled.

[transmitterdan]

Originally Posted by Dockhead

Well, it was designed that way by Yanmar.



It does make me somewhat nervous, however, and it's one reason why i change the oil frequently.

Dockhead,

I'm guessing the oil is hotter than you think. It would take a very large oil cooler with lots of cold water flow to keep the oil lukewarm. That is assuming the fresh water thermostat is correctly rated. If your oil is lukewarm then the engine is being cooled by oil cooler alone. That doesn't seem possible.

Would be interesting to see the water temp. It should be about 180F. Oil should be about 10-20 F more than the water.

[iancoombe]

Just as a recommendation to the op my mechanic tells me not to use synthetic oil in my old perkins 4 108 he likes me to use plain 30 wgt in cold climates and 40wgt in warm. List his reasons but other than lower operating temperature , the rest got lost in translation.

[flyingfin]

Once a year, but NEVER just before or after layup. Have seen people pull the boat for the winter, drain oil and refill. That empties many chambers that dont get re-filled with oil and oil spray coating until you start her up again in the spring. Come spring they have stuck rings and condensation in the valve guides.

[Ken Z]

what color is the oil on the dipstick? change it . save a nickle save a dime screw it up every single time. a bowel movement is like a oil change....🤗

[patprice]

Slightly off topic and apologies but....

For ever I have done the oil withdrawal with one of those little suction pumps looking a bit like a bike air pump but shorter. Has always been a pain of a job, slow and usually messy despite the best preparation.

Alas, I have purchased a real "oil extractor". One of those units nearly a metre high and 200 mm in diameter. Whips the oil out in no time and no scope for leakage. A joy to do the job. Get one!

Now, how to get the bleeding oil filter off cleanly....

Mike, if you are still around Nydri and need a hand with an oil change.....was nice talking briefly with you yesterday.

[Rapanui]

The oil will be a lot hotter before the oil cooler where it is lubricating and partly cooling the engine. The oil cooler reduces the temperature of the oil returned to the sump, so will appear cooler if you touch the sump or filter housing.
The biggest problem with all engines is that if they are run only for short periods and or low power, the oil rarely gets hot enough, so in my view an engine that only does a few hours a year composed of short runs is more in need of an oil change than one doing long hard hours.

[Dockhead]

Originally Posted by a64pilot

Average modern automobile engine's oil temp runs above 200F, usually a little more than the coolant, a lot of performance cars run oil coolers that cool oil with engine coolant, the coolant is of course 195F, so oil has to be hotter than that to be cooled.

Yes, but the oil in my Yanmar is cooled by seawater.

I will check the temp of the oil filter, however -- good idea.

[Wotname]

Originally Posted by Dockhead

Is this realistic? Mine goes through a cooler and never seems to get warmer than lukewarm.

I change every 100 or every 6 months. Whichever comes first.

Originally Posted by Dockhead

Well, it was designed that way by Yanmar.

It does make me somewhat nervous, however, and it's one reason why i change the oil frequently.

Originally Posted by Dockhead

Yes, but the oil in my Yanmar is cooled by seawater.

I will check the temp of the oil filter, however -- good idea.

OK, this really just a guess or perhaps a presumption at best but if Yanmar designed the engine with this oil cooler, it must have been for a reason and the obvious reason is that the oil gets pretty hot somewhere in it's journey around the engine and thus needs to be cooled...

If so, then all is good; the water (and other volatiles) are getting boiled off somewhere in this journey and the oil is getting cooled again ready for it's next circuit.

IIRC, this is a turbo engine and doesn't the turbo (and the oil) get pretty hot around this area.

Or so it would seem to the untrained mind

[Dockhead]

Originally Posted by Wotname

OK, this really just a guess or perhaps a presumption at best but if Yanmar designed the engine with this oil cooler, it must have been for a reason and the obvious reason is that the oil gets pretty hot somewhere in it's journey around the engine and thus needs to be cooled...

If so, then all is good; the water (and other volatiles) are getting boiled off somewhere in this journey and the oil is getting cooled again ready for it's next circuit.

IIRC, this is a turbo engine and doesn't the turbo (and the oil) get pretty hot around this area.

Or so it would seem to the untrained mind

Yes, it's a turbocharged and intercooled, so quite a collection of coolers -- main heat exchanger, engine oil cooler, transmission oil cooler, intercooler. Half of the volume of the engine seems to be various coolers

I took that whole mess apart last year to clean and decalcify and check everything, but everything was clean and fine.

Nothing on this engine seems to get really hot, at least, that you can tell from the outside. The coolant temperature stays at exactly 80.0C no matter how hard or how slow I run it. If it rises to 80.3C, then I know there is a bit of seaweed in the sea water strainer.

I am guessing that Yanmar have done a pretty good job with designing the thermal properties of the engine, but I do change the oil frequently because of being a little nervous about the apparently low oil temperature. I will however shoot the oil filter next time I'm out, out of curiosity.

[Wotname]

Originally Posted by Dockhead

............
I am guessing that Yanmar have done a pretty good job with designing the thermal properties of the engine, but I do change the oil frequently because of being a little nervous about the apparently low oil temperature. I will however shoot the oil filter next time I'm out, out of curiosity.

Is there any access to the inlet side of the oil cooler - again presumably this would be one of the hotter parts of the oil circuit?