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Old 10-04-2019, 07:45 PM   #41
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I hate to break it to but, your engine doesn’t know it’s the end of the season. Just change it at a proper hourly rate. In the construction business some equipment can be used for 300-400 hours then sit in the bone yard for a year not being used. There is no such thing as winter storage. 3126, 3208, 5.9 , JD’s it doesn’t matter. We charge the battery and light them up. Never ever lost an engine to oil.
Agree 100%. Here's a question. How does oil with trace amounts of water, in suspension, in contact with metal parts corrode those parts with a total lack of oxygen? Please, someone, explain the science behind these assertions. I always thought that corrosion can occur only when all of the required elements are present. No oxygen, no corrosion at least in respect to steel alloys.
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Old 10-05-2019, 06:46 AM   #42
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Agree 100%. Here's a question. How does oil with trace amounts of water, in suspension, in contact with metal parts corrode those parts with a total lack of oxygen? Please, someone, explain the science behind these assertions. I always thought that corrosion can occur only when all of the required elements are present. No oxygen, no corrosion at least in respect to steel alloys.

If I'm remembering correctly from what I've learned about oil additives, acids, etc, moisture in the oil can interact with some of the other stuff that ends up in the oil to form acids. So it's possible something like that is happening in the low-volume areas like the oil film left in a bearing and it ends up locally overcoming the oil's acid buffering capacity and causing damage.
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Old 10-05-2019, 07:55 AM   #43
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Agree 100%. Here's a question. How does oil with trace amounts of water, in suspension, in contact with metal parts corrode those parts with a total lack of oxygen? Please, someone, explain the science behind these assertions. I always thought that corrosion can occur only when all of the required elements are present. No oxygen, no corrosion at least in respect to steel alloys.
There is not a total lack of oxygen. The crankcase has several gallons worth of air in it at shutdown. Also, the crankcase is not perfectly sealed, the blowby vent is open and some exhaust and intake valves are open. Rings have gaps. With the wind blowing, some air (not much, but some) moves through engine replenishing the O2 depleted in the corrosion process.

And yes, most corrosion situations are active with the presence of O2, generally dissolved in water. I think in some situations, the presence of some chemicals can strip the oxygen from liquid water to drive the corrosion, but I am no chemist. Maybe David can elaborate on this, he's our resident Chem Engr.

Corrosion does not happen on all engines, but does happen on some. Maybe 5% of the engines I look at have some evidence of this. Just looked at a pair of Yanmar 6LP's yesterday. One was spotless inside, the other had signs of interior corrosion. Exact reason not easy to determine. But it is clear that one engine sat with moisture in the oil. And these also have the sea water oil coolers like the Lehmans. Sale of the boat might be doomed because of this.

If this guy had changed oil before storage, problem might not exist (or be noticed!!) and boat might have sold.
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Old 10-05-2019, 09:13 AM   #44
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Maybe there is dissolved oxygen in oil like water.


Can't say there is...but a few google searches suggest there is and very little oxygen is required to start rust...once it starts, little or none is required for the rust to continue.
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Old 10-06-2019, 05:34 AM   #45
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At big truck repair shops I have seen oil that is designed to evaporate? in the crank case to help protect the engine doring out of service times.


It does not have to be removed . Piston aircraft use a special storage oil, which is removed , saved and used again.
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Old 10-11-2019, 05:22 PM   #46
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The scheduled time to change oil in our Perkins 6.3544 is 250 hours, but I had the old oil assayed before we changed it for the first time, following the 550nm passage from Queensland, because we did not know how long the oil had been in the engine. The only mineral content was a small amount of iron, which the chemist said was consistent with the engine still running in.

I will have it assayed again at around the 200 hour mark, as we do not have an off-season here, and consult the chemist again—he said we may well be able to extend the changes past 250 hours, depending on the condition of the oil.

I am planning on changing it at 250 hours anyway, but the assay will give an interesting series to look at as time goes on.
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Old 10-11-2019, 05:54 PM   #47
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Change it When Necessary

Just my two cents. Modern oils do have a finite life and it varies depending upon the engine and its operation. Changing oil should be based on its properties not how many hours it has on it or how long it will sit. Only a periodic analysis will give a true indication of the need to change the oil. As an example, with 120 hours on a 1600 hour Cummins, the analysis came back as meeting viscosity specifications, flashpoint specifications, no moisture, etc. The TBN was 9.1 on a scale of 1 to 10. Changing this oil is just a waste of a natural resource, time, and money let alone the impacts of oil disposal. Even after a 400 hour season, my analysis showed little contamination and a TBN of 8. An oil analysis is also a critical part of a good preventive/predictive maintenance program since it can provide an early warning of issues prior to them becoming significant.

Large fleet owners rely on oil analysis for a reason - it works!
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Old 10-11-2019, 09:36 PM   #48
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You guys are way overthinking this moisture issue.
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Old 10-11-2019, 11:30 PM   #49
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I don't know if it's right or wrong but I put about 6 hours on my oil after I change it at the end of the season. That's the running time to get to my winter haul out marina where they haul me as soon as I get there.
Once blocked I run the engine enough to get the antifreeze thru the system.
I just sent out oil samples for analysis so I'll know if I am ok or have been doing it all wrong.
Did you send out samples of the old oil or the oil that only has 6 hours on it? I thought you needed to get about 50 hours on the oil in order to get good results from the analysis. Am I wrong about this???
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Old 10-12-2019, 06:44 AM   #50
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I think the 50 hours is for wear trends...less so for contaminants other than metals.
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Old 10-12-2019, 06:50 AM   #51
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Did you send out samples of the old oil or the oil that only has 6 hours on it? I thought you needed to get about 50 hours on the oil in order to get good results from the analysis. Am I wrong about this???
No it was the oil I ran during the season. It had about 80 hours on it.
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Old 10-12-2019, 07:15 AM   #52
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I am about to have my '76 VP hauled out after only 3 hours this season (trying to sell). Time weather over the next week or two will determine if I get a chance to change the oil. It looks clean on the dipstick.
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Old 10-12-2019, 07:26 AM   #53
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While I was in the Army (retired in 2000), Army policy was to change oil only when oil analysis said to. Some of these trucks only drove 1000 miles, or so/year.

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Old 10-12-2019, 07:47 AM   #54
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101% agree. Most oil is changed way before its time. And, I do not buy the moisture "problem". It is not cheapminsurance, just a waste, a waste one is free to make but not I.
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Originally Posted by Senojev View Post
Just my two cents. Modern oils do have a finite life and it varies depending upon the engine and its operation. Changing oil should be based on its properties not how many hours it has on it or how long it will sit. Only a periodic analysis will give a true indication of the need to change the oil. As an example, with 120 hours on a 1600 hour Cummins, the analysis came back as meeting viscosity specifications, flashpoint specifications, no moisture, etc. The TBN was 9.1 on a scale of 1 to 10. Changing this oil is just a waste of a natural resource, time, and money let alone the impacts of oil disposal. Even after a 400 hour season, my analysis showed little contamination and a TBN of 8. An oil analysis is also a critical part of a good preventive/predictive maintenance program since it can provide an early warning of issues prior to them becoming significant.

Large fleet owners rely on oil analysis for a reason - it works!
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Old 10-12-2019, 07:49 AM   #55
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Analysis is definitely the best way to determine change intervals. But for a lot of smaller engines, the oil capacity (and resulting cost to change) leaves it at the point where it's cheaper to just change it a known safe interval than to pay for analysis to stretch it further. I'm definitely in that state, as my 2 engines + generator only take 13.5 quarts total at change time, so buy 4 gallons, that changes everything and leaves some for top-offs.

As far as moisture, it's one of those things that can be a problem, but isn't always. It depends on the engine and usage patterns. Some combos will leave a little moisture in the oil, others will get the oil hot enough for long enough at each run to get it good and dry.
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Old 10-12-2019, 10:45 AM   #56
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Analysis is definitely the best way to determine change intervals. But for a lot of smaller engines, the oil capacity (and resulting cost to change) leaves it at the point where it's cheaper to just change it a known safe interval than to pay for analysis to stretch it further. I'm definitely in that state, as my 2 engines + generator only take 13.5 quarts total at change time, so buy 4 gallons, that changes everything and leaves some for top-offs.
.
Yes I agree. I just paid $28 for an analysis at Blackstone. That's (roughly) half the cost of an oil change that the report might say change it anyway.

Plus I swear I hear my Ford-Lehman saying "Thank You" when I fire it up with fresh oil.
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Old 10-12-2019, 11:59 AM   #57
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Yes I agree. I just paid $28 for an analysis at Blackstone. That's (roughly) half the cost of an oil change that the report might say change it anyway.

Plus I swear I hear my Ford-Lehman saying "Thank You" when I fire it up with fresh oil.
I wish my oil changes only cost $56. My filter runs in the $40+ range and then 4.5 gallons of oil.
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Old 10-12-2019, 12:26 PM   #58
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FF wrote;
“It does not have to be removed . Piston aircraft use a special storage oil, which is removed , saved and used again.”

There’s an idea a bit over the top but using synthetic oil is over the top too.

Using this method for storage just using the oil you usually use but w a much higher viscosity and mono-vis like 50wt. Or even 60wt. The big jump in viscosity would mostly insure a thick coating of oil almost everywhere. You wouldn’t need to dream up or engineer good storage oil. I would think it would be “can’t go wrong ... bullet proof”.

But if one could find a commercially available storage oil that could deal w the chemical issues and beyond. Wonder how much it would cost and how the aircraft oil would perform in boats.
And I think fogging would be an obvious part of this storage gig.

Food for thought for those that want to go the extra mile like syn oil.
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