Am I changing the oil too often?

[Wotname]

Originally Posted by Jim Cate

...... I don't understand what boundary layer erosion is, but can accept that it can cause severe wearing of bits........

Thank goodness I'm not the only one struggling here .
I feel somewhat mollified to know others are in the same boat!

[Jim Cate]

Originally Posted by Wotname

Thank goodness I'm not the only one struggling here .
I feel somewhat mollified to know others are in the same boat!

Well, I kinda know what a boundary layer is, and I kinda know what erosion is, but putting the two together and coming up with rapid and severe wear on steel parts is pushing the limits of my imagination. I am ready to accept the idea when real experts say it is so but would like to actually understand the mechanism, Wottie. (And BTW, I hope that you and Kate are not frozen as of yet).

Jim

[RaymondR]

My relationship with exponents is pretty shaky but an angstrom is 10 to the minus 10 metres so a thousand of the beggars is 10 to the minus seven metres divided by another thousand for millimetres gets 10 to the minus 4 millimetres or 1 ten thousandth of a millimetre. More a very fine polisher than an abrader?

Although diamonds are carbon, all carbon aint diamonds and one of the tricks used by used car salesmen to take the metallic whine out of worn diffs was to put graphite in them, when the lubricating oil would not keep the metals apart the graphite did so. It is also used as an extreme pressure lubricant in very high pressure seals and impregnated into teflon seals for the same purpose to improve wear durability of high pressure hydraulic seals.

I cannot see very fine carbon in lubricating oil as being a significant wear factor in engines although there are a number of other nasties which become incorporated in engine oil that one might not be so liberal with.

A lubricating oil without a boundary layer would not be a very efficient lubricator as the boundary layer adhering to both sliding metal surfaces and holding them apart is what is depended upon to hydrodynamically keep them separated.

Intuitively it would appear that in the event the lubricant film failed a layer of carbon black retained between the metal surfaces might help prevent excessive wear of the surfaces.

It's all to much to worry about so I'm going to stick to my once a year oil change on my sail boat and rethink it if I become a stink boater.

[Simi 60]

250 hour changes on the main engine with 37 litres in it
Oil is still clean as in I can very clearly see the levels marked on the dipstick.

100 hour change on genset, I have now started feeding it the 250 hour oil from the main and running for 50 hrs between drops and 100 on filter.

[Kenomac]

Considering modern improvements regarding synthetic oils, I think changing the oil and oil filter once per season, with less than 300 hours is good enough. We rarely have even 200 hours per season on the engine or generator. Neither our generator or Yanmar 100hp burns any oil or smokes at 18years old with 2200 hours.

Sometimes a little soot around the water separated exhaust pipe, but that’s to be expected.

[valhalla360]

Going to something crazy like 500hr can create other issues as additives are used up, sludge forms and other things happen....

But within more reasonable change intervals, how many marine engines actually die from internal wear? All this talk about soot abrasion, I believe may be a red herring. Marine engines have the advantage in typically NOT operating in a dusty environment. I can't prove it but my belief (can't prove it) is that this is mostly an academic discussion. There may be less wear but if it's the difference between a 20,000hr expected life and 22,000hr expected life for an engine...the vast majority will never see an impact.

[a64pilot]

Soot has nothing to do with dust, it comes from the combustion of fuel.
People will believe what they want to, it’s human nature.
My only point in all of this is that we should change oil in a Diesel due to contamination of the oil, not due to oil breaking down, which is of course what all the oil ads talk about, to push the superior qualities of their oil over others.

“Real” synthetic oil has qualities that make it far superior to “regular” oils, in use cases that push oil hard, think high revving, very high oil temp racing turbocharged type engines for example, but the average low revving, low temp Marine Diesels just may not benefit much from these superior, but higher priced oils.

Just do NOT fall into the trap of I’ll use expensive, high quality synthetic and then I’ll only have to change oil half as often. That’s actually saving me money buying the expensive oil. It’s not, but it’s a great marketing position, if your selling synthetic oil.
If you want to extend oil change intervals, don’t without going to high bypass filtration to clean the oil as clean as you can.

Now I’m not against synthetic oil, in truth I have run it in everything I have except my airplanes and now my boat, for decades.

Like I said, if you have a newish engine and won’t likely keep the boat all that long, don’t worry about it, you won’t wear out the engine.
However if you have any concern about repowering in the future, but you have a high time but good running motor now and are wanting to extend its life as long as practicable, well then maybe consider frequent oil changes.

Or not, your choice

[valhalla360]

Originally Posted by a64pilot

Soot has nothing to do with dust, it comes from the combustion of fuel.

I wasn't suggesting soot = dust.

One of the primary sources of abrasive contaminants in engine oil is dust pulled thru the intake that gets past the air filter and winds up in the oil. This is why operating in dusty conditions is often listed in car/truck owners manuals as a reason to use a shorter oil change interval.

But in a marine environment, dusty conditions are usually (but not always) less of an issue.

Back to my original point...you don't see a lot of engines wearing out due to lubricant related wear. As long as you don't go crazy with excessive time between oil changes (like 500hr), you simply aren't going to wear out an engine because of your oil change regimen.

[a64pilot]

You do see a lot of engines burning oil, which is almost always a direct result of wear.
People usually replace engines for one of two reasons.
1. A catastrophic event, like seized from overheat, or ingestion of water etc.
Many catastrophic events are the result of wear, thrown rod, spun bearing etc. or poor maintenance.
2. Wear, usually manifests itself in burning oil, low power and hard or start, all of course upper cylinder wear, but sometimes lower end, low oil pressure, spun bearing etc, but it’s all the result of wear.

1. Can usually be mitigated by good preventative maintenance and or design, but once in a blue moon a bad part does slip by, and that is unpreventable by the end user.
2. Can be greatly minimized by good preventative maintenance.

You can greatly extend the life of an engine by good PM, and of course how it’s operated.
Both of which you are in complete control of.


I’m not saying your going to die if you don’t change oil more often than the manual recommends, that’s silly, and I’m not saying your motor will seize if you buy an orange Fram filter, that’s silly too.
However I am saying that your engine will run for many more hours if you shorten change intervals, and use a quality oil and filter

[valhalla360]

Originally Posted by a64pilot

You do see a lot of engines burning oil, which is almost always a direct result of wear.
People usually replace engines for one of two reasons.
1. A catastrophic event, like seized from overheat, or ingestion of water etc.
Many catastrophic events are the result of wear, thrown rod, spun bearing etc. or poor maintenance.
2. Wear, usually manifests itself in burning oil, low power and hard or start, all of course upper cylinder wear, but sometimes lower end, low oil pressure, spun bearing etc, but it’s all the result of wear.

1. Can usually be mitigated by good preventative maintenance and or design, but once in a blue moon a bad part does slip by, and that is unpreventable by the end user.
2. Can be greatly minimized by good preventative maintenance.

You can greatly extend the life of an engine by good PM, and of course how it’s operated.
Both of which you are in complete control of.


I’m not saying your going to die if you don’t change oil more often than the manual recommends, that’s silly, and I’m not saying your motor will seize if you buy an orange Fram filter, that’s silly too.
However I am saying that your engine will run for many more hours if you shorten change intervals, and use a quality oil and filter

And I'm saying it doesn't make a lot of difference unless you go to extremes. Which I suspect is the situation with a lot of engines that burn significant amounts of oil or are down on power. Most engines I've personally seen, you can trace it back to abuse.

Do you have any empirical evidence to support that you will get many more hours if you shorten change intervals? If so, how many extra hours can be expected for various changes in intervals?

Looking at the automotive side (far larger sample size and more consistent usage patterns), it's very rare for an engine to "wear" out. Yet, maintenance is all over the place.

[Wmkenney]

The answer is no, you really can not change the oil too often, however it is a waste of $$. In my 25 years experience working in the automotive world, I strongly suggest you follow the manufacturer suggested Interval. You can improve the filtration quality by using a better filter usually. As far as the synthetic question.....follow the manufacturers suggestion again. Non synthetic oils usually Include hard metals which most synthetics do not, which can and does create issues.

[Dockhead]

Originally Posted by valhalla360

. . All this talk about soot abrasion, I believe may be a red herring. . .

No need to guess about this; there is abundant information available concerning the abrasiveness of diesel soot and the effect of soot in the engine oil on diesel engine wear. Here in one paper, more than you ever wanted to know, from the SAE in fact:


http://w124performance.com/docs/gene...ts_Of_Soot.pdf



"Abstract: During the diesel engine combustion process, soot particles are produced and are either exhausted into the atmosphere or absorbed by the engine’s lubricant. Soot-contaminated lubricant has been shown to produce significant amounts of engine wear. The main mechanism of soot-related wear is through abrasion, but, at increased levels of soot content in the lubricant, starvation of the contact can occur, which can increase wear further. High concentrations of soot can increase the local acidic level and, around the piston where high temperatures and volatile gases coexist, corrosion may also occur. In this paper, the current understanding of engine wear due to soot contamination and the previous research performed is reviewed. The paper also discusses soot formation and its general effects within the engine(including friction and efficiency), as well as other issues including filtration or removal, effects on the lubricant, engine design and operation, and future industry targets and technologies related to soot contamination."



So do we not care about that, because we are unlikely to wear out our engines anyway? Because we don't use them enough hours a year to wear them out before they rust apart?


Everyone will have to answer that for himself. For my part, however -- I had over 20,000 hours on the engine in our last boat, and am closing in on 4,000 hours on this one. I've seen badly maintained marine engines start to burn oil and have starting problems from low compression at less than 3,000 hours. I don't know about you, but I have always been careful with oil changes, and don't plan to change.

[GeneM]

That's good. I do it every 200 hrs on my Cummins 5.9's. You can go 500 only if you have a bypass filter.

[sailorboy1]

This thread has been a lot more friendly than a similar one I started once here when I wanted to go changing the oil every 300 hours

[Lepke]

I've used bypass filters my whole life. Early Detroit Diesels and most cars in the mid 1950s only had a bypass filter. When I was young, and there were fewer engine brands, I ran the same engines many others did. With really clean oil, I often went double the hours between rebuilds as others. Now I centrifuge my oil every 50-100 hours. I take a sample before cleaning and get excellent tests. I haven't actually changed oil since 2011, just add makeup oil.

My current Detroit mains were built in 1947 with stock bypass filters. The engines weren't rebuilt until I did it 8 years ago. I doubt they'll ever be rebuilt again before some new propulsion method makes diesel obsolete.