Does lightly used oil deteriorate over time?

Daveo said:

I’ve recently been told, while at an engine manufacturers training course, that the typical New England temperature changes over the winter will destroy the additive package in new oil installed when boats are hauled for the winter necessitating a change upon launch in the spring even though the oil was never used. This due solely to condensation inside the motor as the temperature fluctuates. These people are only concerned with maximizing engine longevity and maintaining their reputation, they are not selling oil or oil changes.

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ok

Sounds fishy to me

Daveo said:

I’ve recently been told, while at an engine manufacturers training course, that the typical New England temperature changes over the winter will destroy the additive package in new oil installed when boats are hauled for the winter necessitating a change upon launch in the spring even though the oil was never used. This due solely to condensation inside the motor as the temperature fluctuates. These people are only concerned with maximizing engine longevity and maintaining their reputation, they are not selling oil or oil changes.

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So let me get this straight. A New England fishing boat that sits for a week over Christmas would have to change oil because the additives would be destroyed?


Hmmm. The us srmy, which owns tens of thousands of Diesel engines changes oil when oil testing specifies. Many of these vehicles sit for weeks at a time and the oil may be changed once in five years.

If you are getting that much condensation in your engine you have other problems. This ranks up there with keep fuel topped off to reduce water in the fuel.

Gordon, who has never had a problem with water in fuel or oil.

Would a few liters of gun oil be the answer ?

Daveo said:

I’ve recently been told, while at an engine manufacturers training course, that the typical New England temperature changes over the winter will destroy the additive package in new oil installed when boats are hauled for the winter necessitating a change upon launch in the spring even though the oil was never used. This due solely to condensation inside the motor as the temperature fluctuates. These people are only concerned with maximizing engine longevity and maintaining their reputation, they are not selling oil or oil changes.

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If that’s the case, drain the oil in the fall, put it in a nice warm garage for the winter, and put it back in the spring (after draining out all that condensation, of course.)

Lou_tribal said:

Hum if true I would suspect more engine failure in boats, and cars, up here than any other country

L

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Been doing it that way for 30 yrs and so far no engine problems. Think I'll stick to my old habits.

That strikes me as a pretty far fetched claim when any SMALL amounts of water will remain separated from the oil with engine sitting idle.

I'd like to see some valid test data to substantiate a claim like that before I acted on it.

That claim, despite the authority supposedly behind it, is just nonsense.

On one hand, it just doesn't pass the smell test of simple physical reasoning. A non-running engine isn't going to generate the heat that is required to generate condensation - it will have only a very trivial amount in it from the last condesnation.

Here's some real data. 25 year old Deere, laid up on the Great Lakes over winter, year-old oil, heavily used (500hrs, albeit much make-up oil in the interval). Just fine come spring.

https://www.bobistheoilguy.com/foru...marine/Search/true/6076_Deere_UOA#Post4433182

Be careful, like condensation in partially full or almost empty tanks.....it depends a lot in where you are climate wise.

I have seen engines dripping in sweat after a cold snap or just cold engine rooms from the water, and a warm, moist front passes through. If you don't have your exhaust and intake sealed up tight, the water could add up.

Now the question is.....how much does it take to deteriorate the oil?

"If you don't have your exhaust and intake sealed up tight, the water could add up."


Sealing the engine is usually part of the "out of service" tasks in most engine manuals.( Da Book. )


Its fast ,& cheap so why not?

Engines oil crankcases are well sealed from the atmosphere, internal condensation inside the block? LOL. All internal surfaces are heavily coated with a film of oil and also oil varnishes.
A cylinder wall can rust but changing oil won't help that.

You would think nothing of parking your car all winter in New England without changing the oil before and / or after. What’s different? One reason for getting any engine up to operating temp is to boil off moisture internally and externally. Unless someone or something is pouring water into your crankcase you are fine.

Easting said:

You would think nothing of parking your car all winter in New England without changing the oil before and / or after. What’s different? One reason for getting any engine up to operating temp is to boil off moisture internally and externally. Unless someone or something is pouring water into your crankcase you are fine.

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What is different, is its a boat, and marinas convince boat owners to spend their money at the marina, in this case by scare tactics, seeing a marine engine is a pricey piece of technology, people weigh the cost-benefit in their heads and some do trust what these 'experts' tell them.

well, parking a car all winter without ever driving it...how many do that?

another car to boat comparison that I'm not sure works completely.

psneeld said:

well, parking a car all winter without ever driving it...how many do that?

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I do and a lot of people doing it up here.

L

Most cars are gasoline , so the choke plate and throttle plate should slow down a breeze.

The muffler and cat converter would also slow the breeze.

Changes in atmospheric pressure would be only air motion , and might no be enough to refresh water vapor in the cylinders.

FF said:

Most cars are gasoline , so the choke plate and throttle plate should slow down a breeze.

The muffler and cat converter would also slow the breeze.

Changes in atmospheric pressure would be only air motion , and might no be enough to refresh water vapor in the cylinders.

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choke plate and throttle plate ?

Oil Analysis ..... not all it's cracked up to be.

"choke plate and throttle plate ?"


Inside a carburetor , usually closed while not underway.

FF said:

"choke plate and throttle plate ?"


Inside a carburetor , usually closed while not underway.

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Did them old fashion cars have them ?

psneeld said:

well, parking a car all winter without ever driving it...how many do that?

another car to boat comparison that I'm not sure works completely.

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"well, parking a car all winter without ever driving it...how many do that?

another car to boat comparison that I'm not sure works completely."

Some do. I have. Farm tractors by the thousands

anectdotal evidence is nice, but usually everyone changes their minds when a little scientific proof is brought up....

when the comment was made about marine engine manufacturers suggesting changing oil again in the spring...I was looking for some science, not cars and tractor winter habits....conditions are not always the same between driveways, barns and bilges....even in the same town. Nor even similar boat situations...

but like most, I was always a Fall oil changer and Spring start and go type.

I like to hear better ideas about old habits, they just need a bit of meat on their bones either way.

I tend not to worry about how old the oil is in a machine in terms of calendar time. But whether gas, diesel, road or marine, I make a point of making sure engine runs fairly hard under load prior to going to storage. This is to cook out any moisture from the oil.

Storing with dry oil, no worries.

Storing with oil that has moisture in it, trouble.

My pickup truck (gas) often sits in the garage for a month if I am on a trip or otherwise not needing it. Before I park it the last time, it goes on an at least 15mi trip to run chores, with at least some at highway speeds. Then in the garage to sleep. Since I don't drive it much, sump oil might be in there three years before a change. Looking at valve gear through the oil fill hole, valve gear is still nice and clean.

Worst thing are these guys with classic cars that crank them up and idle them around all the time, then let them sit. Engines get nasty.

And Detroit Diesel guys need to be particularly careful with storage due to the unique two stroke flow path. Can rust liners way quicker than a four stroke.

"And Detroit Diesel guys need to be particularly careful with storage due to the unique two stroke flow path. Can rust liners way quicker than a four stroke."

True , but after the gasket on each air box cover is renewed spraying INTO each cylinder is a simple 1 bolt R&R and a can of fogging fluid. A few min and a $5.00 can of fogging fluid will last almost a decade.

Only hassle is on first out of storage start , it will kill flying bugs for 5 miles!

TDunn said:

The oil itself won't break down, after all it is millions of years old (unless you use synthetic). However, the additives could deteriorate and the oil will pick up moisture and become acidic. I would look at it by pulling the dip stick and wiping it on a white paper towel. If the oil looks new you are likely good to go. If it is black (carbon accumulation) a change would be a good idea.

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With Bay Pelican's Lehman 135 the oil looked black after 1 hour of operation.

"With Bay Pelican's Lehman 135 the oil looked black after 1 hour of operation."

This is because the modern full flow oil filter does a poor job of filtering the fines.

A second bypass oil filter will mostly solve the problem.

Here is one style,

https://www.dieselcraft.com/engine-oil-cleaning/

FF said:

"And Detroit Diesel guys need to be particularly careful with storage due to the unique two stroke flow path. Can rust liners way quicker than a four stroke."

True , but after the gasket on each air box cover is renewed spraying INTO each cylinder is a simple 1 bolt R&R and a can of fogging fluid. A few min and a $5.00 can of fogging fluid will last almost a decade.

Only hassle is on first out of storage start , it will kill flying bugs for 5 miles!

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If you fog a DD through the airbox, AND bar it over to fog all holes, you are doing it right.

"AND bar it over to fog all holes, you are doing it right."

Way too lazy to bar by hand !!,

I bump the starter to get the pistons out of the way.