Water in the Engine Oil

[Don L]

The oil change thread got me thinking. Water in the engine oil over time from condensation is a common thing written in threads. But is it real or a myth? I have never seen any water evidence in the oil I have changed out and once I had some test strips and never saw it then. So ............

How many have seen this water in oil from a non water/coolant leak into the engine just from an engine sitting around or not running long enough? I bet there are many here who do routine oil analysis on their engines, how often does it come back with water in it?

[psneeld]

https://www.machinerylubrication.com...hygroscopicity.

"Oils by nature are hygroscopic, which means they absorb moisture from the air. The tendency of an oil to undergo this process is known as hygroscopicity."


https://www.brookfieldengineering.co...e-headed-beast


Dissolved Moisture
Dissolved moisture is the lowest level of moisture contamination in lubricant oils. This moisture is derived from ambient air humidity slowly interacting with the lubricant oil overtime. Usually, the more additives the oil contains, the more hygroscopic (water attracting) the oil will become. Acceptable levels of dissolved moisture typically range from 50-300 ppm (or 0.0050% – 0.0300%). [2] This level of moisture does not greatly affect the compressibility or viscosity of the oil but is the most chemically reactive water species since it is dispersed throughout the oil.

The bottom line:
Dissolved water can degrade metal and deplete additives

Direct Effects

Dissolved water molecules will coat any polar metal surface it finds within the engine. Under routine engine pressure and heat, this small amount of water can be stripped of its oxygen constituent and release hydrogen ions, which will chemically degrade the face of the metal (ball bearings and gears). This weakens the metal and microscopic flakes will begin to shed from the metal leading to particulates in the oil leading to gear corrosion.

Indirect Effects

Dissolved water molecules will actively seek other polar molecules which may include additives such as detergents, antioxidants (amines or phenols), friction modifiers, and anti-wear additives (such zinc phosphates). Because water molecules are sequestering these agents, these additives lose their functionality which may cause problems to the engine.

[Brooksie]

Mostly a myth. Maybe a few drops if boat stored in a cold damp climate like New England but that amount would boil off in moments of running. I know people that start their engines every month while in storage and run it for 1/4 hour during which the oil never reaches operating temperature although the coolant may. I imagine those people have more condensation.

[rgano]

It's got to be pretty difficult for air to breathe in and out of a sitting engine to produce any significant condensation, just as I have never seen evidence of condensation in fuel tanks. If you have doubts about your oil after a long term boat storage, get it tested.

[Don L]

I tried google searching and mostly decided the answer appears to be

yes

But it is unclears what the question was.

[psneeld]

Originally Posted by rgano

It's got to be pretty difficult for air to breathe in and out of a sitting engine to produce any significant condensation, just as I have never seen evidence of condensation in fuel tanks. If you have doubts about your oil after a long term boat storage, get it tested.

I often found liquid water droplets uner my Lehman valve cover. So there is some atmoshperic transfer to some engine areas as well as liquid water getting in the oil.

Fortunately I ran my engine enough and changed the oil enough that analysis never showed significant amounts of water in the oil, so analysis is a good alternative to a calendar change.

Modern engines may be tighter and more resistant to getting atmospheric water in them. Making analysis all that more valuable.

[TowLou]

In many motors due to different fuel sources I have seen water in the oil from condensation. LPG ran motors are good for that if they do not get warmed up.

Diesel engines most water in the oil was from outside sources causing failure. Seen coolant from the head or rain water through the exhaust. Pulled a few gallons out of one motor. That one was definitely internally damaged.

Also how warmed up does the oil get? Warmer the better to help keep the condensation away. A coolant bubbler little 500w or block heater when sitting could help with it getting cold enough to condensate.

[dannc]

I just looked at my oil tests going back to 2012. I have tests going back farther but I can't find the digital reports. Any who, that is a decades worth of tests and there is no water in the oil samples.

This is a truck engine but we do live in a hot and humid environment.

Later,
Dan

[psneeld]

My results were negative too, but regularly used engines seem to not suffer like stored engines or little used ones in boats.

Maybe why engines in commercial marine applications seem to live longer.

[dannc]

Originally Posted by psneeld

My results were negative too, but regularly used engines seem to not suffer like stored engines or little used ones in boats.

Maybe why engines in commercial marine applications seem to live longer.

I would think under used engines might have a problem with with water in the oil. But what does "under used" mean?

In my case, my truck is being used once in one week or maybe two since the pandemic. After it has been sitting for a week or two, I do try to drive it for 20 minutes or so. Even with the last oil change, which was almost 3.5 years on the oil, and very low miles, had no water. It COULD be that the oil is collecting oil but I am burning it off when I do drive the truck since I do go for a time period and speed, to warm up the engine and keep it hot for a 15-20 minutes.

I did find some oil reports back to 2010 and no water in the oil but until the pandemic the truck was used 5-6 days a week.

Later,
Dan

[Bacchus]

Originally Posted by rgano

It's got to be pretty difficult for air to breathe in and out of a sitting engine to produce any significant condensation, just as I have never seen evidence of condensation in fuel tanks. If you have doubts about your oil after a long term boat storage, get it tested.

I have to agree 1000% with Rich...
My oil analysis on boat and land Yacht have never indicated a moisture issue.
MANY boats up north here sit for 6 mos on the hard. I would think if oil attracting & absorbing (wrong term I'm sure) moisture were a significant issue 6 mos of storage, w/o running to drive it off, would be a perfect case where it would manifest itself. Most boaters I know change oil in the fall, before storage, and I've never heard of owners finding moisture issues in the spring.
Think about it... the engine is buried below decks and changes temp very slowly compared to the outside environment. It "inhales" environmental air as it cools and there is a significant lag time. The result is the engine is inhaling cold air (which has less ability to hold moisture than warm air). When environment is warm and can hold more moisture, the engine is warming (again w time lag) and exhaling so no moisture introduced internally. You might see external condensation on cold metal parts in a humid environment... but if the engine is warming it is exhaling so no moisture aspirated.

I agree the situation is different in (humid) coastal areas with engines run periodically... they cool from operating temp to ambient every cycle and can inhale humid air, however, if run enough to reach full operating temps moisture should be driven off. This the importance of running longer & harder than just to "circulate the oil" which some novices be.ieve is better than not running but IMO and many others, that's flawed logic.

If you run them... run long / hard enough to reach full oper temps or don't run them at all!

[Pete Meisinger]

I am saying it is a myth. Makes one wonder about the same myth regarding condensation into a fuel tank. (I'm not a big believer in that either)

pete

[BeeJay]

Hmmmmmm…….. take some water and put it in a jar, pour some oil on top of the water. Replace the lid and shake. See how they mix ……..hmmmmm….maybe you have to shake it real hard.

[Don L]

What?

[sunchaser]

Spend some time around a diesel fuel farm or on board a large multi thousand gallon vessel and the “myth” of water in fuel will take on a bit of truism.

Water in our lubricating oil is a different story. It normally comes from a failing head gasket, oil cooler or after cooler.

[Pete Meisinger]

Water from condensation inside an engine would only be a tiny amount, if any. It would probably get burned off from engine heat.

pete

[jleonard]

I got water in a fuel tank once from condensation.
I was on the hard in Mystic , Ct. The guy next to me on the west side built a “shed” over his boat so he could do a major job on his boat over the winter. He used a green tarp.
I believe this created a sudden temperature drop once the sun got blocked out thus creating condensation in my port tank, the side his shed was on.
When I fired up in the spring to put over to a slip for the day ( 3 to 5 minutes at idle) and then did an engine room visual, I saw the Racor 900 bowl almost full of water.
Dramatically Ned it then returned following weekend with an outboard engine squeeze ball rig. I was able to make the boat list to a corner and sucked out water in ntill I was getting diesel.
All in all I got about 1 quart of water.

[Don L]

Topic is about condensation in an engine, at least is what my intent was.

[Steve DAntonio]

Free water accumulation in oil, from "condensation" is, in my experience, myth. I've been doing oil analysis for 20 years, and virtually the only time I encounter flag worthy levels of water in engine oil, with rare exceptions, it is as a result of exhaust system defects.

[TowLou]

Speaking of condensation and todays find even tho a natural gas motor. Do not be fooled that is a oil breather filter.

In my experiences its from the engines any fuel source (gas, diesel, LPG, Natural gas) a lot of it has to do with not coming up to temperature or not ran long enough with a load or even a stuck open or no thermostat. Any combination even to plus how cold is the water coming into the heat exchanger matter on a boat. Have even some older marine gensets with heat exchangers plumbed to city water I see.

That motor there never got over 160 in 90 degree weather with 170 amp load for a 250kw genset. She had the load to warm up Im betting a stuck open thermostat or maybe one to low of a openning.