Am I changing the oil too often?

[denverd0n]

Originally Posted by Lepke

The only harm to your engines from changing the oil too often is the engine will last longer because of less debris in the oil.

The other harm is to your pocket book, if you are spending money on something that derives no benefit. Hence the question, how often is often enough, without being too often?

Originally Posted by Sojourner

So tangent question: my engine was not rebuilt properly and Smokes and eats a liter of oil per 40 hours. Not getting back to repairing it till winter. Do I still need to change the oil or just the filter if I go over 200 hours before then? It's all brand new oil effectively...?

No, it is not all brand new oil. The oil burns off, but leaves most of the contaminants behind. Your oil is progressively getting worse and worse. You definitely still need to change your oil -- not less often, but probably more often!

[valhalla360]

If we assume similar stress levels (ie: you aren't running that little diesel at 90% of peak output)...200hr would be similar to running a truck at 60 mph for 12,000 miles between changes.

500hr would be equivalent to 30,000 miles between changes. That strikes me as a lot.

I may be off on my assumptions of equivalency but 60mph freeway driving is light duty use pattern.

[hpeer]

I have a slightly different dilemma. My 35 year old Volvo MD7 says 20/30 weight oil (above 10°C) and 10 weight below, and change every 50 hours. First, where I am I can’t get 30 weight oil let alone 10. I can get either 10w-30 synthetic or 15w-40 classic oil. Engine has about 1,000 hours on a full, professional rebuild. Previously I’ve always changed oil at 50 hours or real close. It’s right black by then.

I’m looking at a longish trip where I will have in-route oil changes. 3°C water.

I’ve stocked up on the 15w-40, and a bunch of oil filters. I think I’ll extend the oil change to 100 hours. Changing oil underway, open ocean is just too much fun, I need to resist the urge. (Scarc)

Then there is the transmission which also wants 30 or 10 weight. I can probably find a couple of quarts of that in a non-diesel blend.

[GordMay]

Originally Posted by denverd0n

... No, it is not all brand new oil. The oil burns off, but leaves most of the contaminants behind. Your oil is progressively getting worse and worse. You definitely still need to change your oil -- not less often, but probably more often!

Counter intuitive, but entirely plausible.
You've convinced me (to change my mind). My opinions may have changed, but not the fact that I am (now) right.

[Dockhead]

Originally Posted by GordMay

Counter intuitive, but entirely plausible.
You've convinced me (to change my mind). My opinions may have changed, but not the fact that I am (now) right.

I had this argument with my father when I was 12 years old.


We had an old 1964 Impala wagon with a 283, which burned oil like crazy. My father thought that because we added a quart of oil every time we bought gas ("fill up the oil and check the gas, please!"), that we NEVER needed to change it. I disagreed. He won. Don't know who was right; we soon got sick of it and sold the car.


On the basis of no specific knowledge whatsoever, I am going with DenverD0n's position.



But it's logical -- you are renewing the oil this way (good) but you are not getting rid of the garbage (bad). With slightly old fashioned marine diesels like most of us have, I think taking out the garbage is the real problem, not the oil wearing out. Our engines have practically unlimited cooling capacity. Even fresh water cooled ones run at only 80C (most of them), and the oil is probably not warmer than that (my Yanmar has a great big oil cooler). We typically run them at 20% or less of their maximum power. The oil as such doesn't break a sweat; it would probably last 1000 hours if it were not for all the crap -- abrasive soot, and corrosive acid -- which collects in it. There is no need for synthetic oil and no basis upon which to hope to stretch the oil change intervals -- in my opinion. Just use the recommended oil and change it as often as you can, and in no event less often than the manufacturer specifies.

[a64pilot]

Originally Posted by Lepke

The only harm to your engines from changing the oil too often is the engine will last longer because of less debris in the oil.

This is your answer.

In short most of our engines stress oil very little, we don't change oil because it breaks down, good oil, especially synthetics would last for hundreds of hours before any detectable loss or increase of viscosity.

We change oil because it gets soot laden, soot is carbon, and carbon is very abrasive, oil is still fine, but full of wear causing soot particles.

Using Synthetic oil in even old motors wont cause any harm, in fact its excellent oil, but likely completely unnecessary in our motors.
Exception may be turbo motors run hard.

If you want to keep your motor for a very long time, change the oil every 100 hours or maybe even less.

Do NOT go to extended oil change intervals, unless you also have good, high bypass oil filtration, then you can likely go for very long intervals.
Use oil analysis to determine change interval if you have high bypass filtration.

Our tiny little oil filters just cannot filter very fine and still allow the volume of oil flow the engine needs, if you want to filter well, you need a big filter and only filter a small part of the total flow as a fine filter is a lot of restriction


The older an engine is, the more frequent the oil ought to be changed, due to old motos have more blow by, and blow by is the source of most of the carbon.

Contrary to popular opinion a high quality oil isn't one that doesn't turn black fast.
A high quality oil turns black fast cause its doing its job, its cleaning the inside and keeping that carbon in suspension.

You can find studies to support any position you want to take, there are many different reasons, one is its not environmentally friendly to change oil often.
The only real use of SOAP or spectroscopic oil analysis programs is to determine when the oil should be changed, its not an engine analysis as its marketed and many want to believe it is, its an oil analysis.

What we ought to have is something like GM's GMOLS which is software that tracks how many time the engine is cold started, if it fully warmed up, how hard it was run etc and triggers the change oil light not on hours or miles but when the system has determined the oil should be changed.

But we don't, so you have to determine how important that motor is to you and act accordingly.

[a64pilot]

Originally Posted by valhalla360

If we assume similar stress levels (ie: you aren't running that little diesel at 90% of peak output)...200hr would be similar to running a truck at 60 mph for 12,000 miles between changes.

500hr would be equivalent to 30,000 miles between changes. That strikes me as a lot.

I may be off on my assumptions of equivalency but 60mph freeway driving is light duty use pattern.

Nothing ever averages 60 mph, actually less than 30, that sitting at a stop light really kills average speed.
we put over 50,000 miles on a car each year the first couple of years we owned it, so of course that was mostly all highway miles, and that car tracks average speed, and its average was almost always in the 20's MPH.

So triple your example

[donradcliffe]

Originally Posted by undercutter

Main 135hp with 13 litre
Genset 30hp 3 litres

What is the significance?

The larger the sump capacity, the lower the concentration of contaminants. I remember a friend with a 60 hp Mercedes engine with 12 liter sump. Theoretically the oil change interval for that engine should be longer than your 13 liter 135 hp engine.

However, there are a lot of other factors. Most of the information on oil change intervals is marketing based, but I found some interesting information in

https://www.machinerylubrication.com...ange-intervals

[a64pilot]

Look this is the bottom line.
OIl is at its best when it comes out of the can, from that moment on, it starts to accumulate particles that cause wear, our stock filters don't filter fine enough to remove all of those particles, just the biggest ones.
It up to you to decide how many particles that cause wear your willing to let accumulate before you need to change the oil.

Modern spark ignition engines are a completely different animal, they run exceptionally clean, especially if run on propane, a Propane motor may could go a very long time for example, likely a good synthetic and a good filter could last the life of the engine

[PamlicoTraveler]

On the 4jh57 Yanmar says to change the engine oil after the first 50 hours of operation, and after that every 250 hours. (API Service Categories CD, CF, CF-4,
CI and CI-4.)

[a64pilot]

I'm not necessarily an Amsoil fan,but this explains high bypass filtration for those that want to extend change intervals
https://www.amsoil.com/bypass/how-it-works.aspx

[RobinScurr]

It's my understanding with diesel engine oil that it's the ADDITIVES to the oil that are the issue. There are compounds to neutralize any sulfur that gets into the oil, so it does not become sulfuric acid? You'll use the additive up long before the oil isn't lubricating properly. And as such, there's little/no value to synthetic oils... they have the same additive issue as conventional oil.

Follow the engine manufacturers recommendation for interval AND oil rating. Old engines have a very hard time finding an appropriate oil to use, as the older standards aren't made any more.

Using the "newest and best" synthetic oil in a 35 year old engine is, apparently, a bad idea.

[a64pilot]

Originally Posted by RobinScurr

It's my understanding with diesel engine oil that it's the ADDITIVES to the oil that are the issue. There are compounds to neutralize any sulfur that gets into the oil, so it does not become sulfuric acid? You'll use the additive up long before the oil isn't lubricating properly. And as such, there's little/no value to synthetic oils... they have the same additive issue as conventional oil.

Follow the engine manufacturers recommendation for interval AND oil rating. Old engines have a very hard time finding an appropriate oil to use, as the older standards aren't made any more.

Using the "newest and best" synthetic oil in a 35 year old engine is, apparently, a bad idea.

What you are describing is Called TBN, or “Total Base Number” it’s a measurement of how much acid an oil can neutralize, if your doing oil analysis to determine oil change interval, it occurs when the TBN and TAN “Total Acid Number” cross on a graph, that is when your oil no longer can neutralize the acid.
US Army changes oil based on analysis and has done so for decades, and has saved the taxpayer and the environment no telling how much as most of their engines just sit in the motor pool.

Anyway, for ever one of the hallmarks of a premium oil was a high TBN, of course that oil can neutralize much more acid than a low TBN oil can, and as additives cost money, it’s cheaper to manufacture a low TBN oil.
There has been one expert suggesting that a high TBN oil will cause bore glazing, I think that a ridiculous statement for several reasons, for one TBN is a measurement of the total base of an oil and that can be derived at many different ways, used to be zinc, but to say that any chemical that makes an oil basic will cause bore glazing is sort of stretching it, in my opinion.

Then maybe you need to understand that you pretty much can’t buy a high TBN oil anymore, the high TBN oils are special oils made for the very few engines that can still burn high sulphur fuel, maybe trains, ships etc., but high sulfur fuel must be hard to source?
Since fuel became ULSD, the TBN isn’t as needed as it used to be, and zinc is no longer used as it can poison catalysts, so the TBN of premium oils is much lower as it’s not as required as it used to be.


Anyway all of that pretty much means that acid formation isn’t as big as an issue as it used to be, not if your burning ULSD anyway, so we are back to soot build up being the primary driver of oil changes now.


It’s kind of similar to the removal of lead from gasoline in I guess the 70’s. Once lead left, oil can last much longer now, and spark plugs can last for Extremely long time now.
Removal of lead really changed the maintenance intervals of some items drastically, as well as other advances of course, but no lead is a lot of it.
https://www.ccjdigital.com/partner-s...-engine-oils/#
https://www.ghberlinwindward.com/tbn...l-engine-oils/

[doublewide]

There is no harm, other than cost, in having fresh oil in the engine. I always change mine before a long lay-up, for example, even though it has not "timed out" yet.
On the other hand, it is best not to change the filter too often. Oil filters filter better in the second-half of their lives than in the first-half. Because the filter holes get functionally smaller as the filter slowly plugs up. So be sure to always use the second half of your filter's expected life before changing to a fresh filter.

[undercutter]

Well lots of good information and thanks for that.

I will say that after the first 100 hours the oil is hardly dirty at all and she never loses a drop between oil changes so she must be pretty tight. The engine has dual oil filters which are of course changed every time the oil is. 4000 hours and she runs like a top so I guess I will continue with the 200 hour intervals.

I do believe that the synthetic oil is better in the genset so I guess I will continue with that again changing the oil at the recommended intervals. It is only 3 litres so not a huge cost. The single filtre is also tiny....