Frequency of lube changes

   #1  

citytransplant

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1. It's my understanding that engine oil breaks down over time, regardless of engine operation. That is to say oil should be changed at certain time intervals even if the engine itself hasn't been used much. If true, why does unused engine oil still in the container have an indefinite shelf life (or does it)?

2. Owner's manual for my Farmtrac 27 hp notes that hydro fluid should be changed every 400 hours. While I've owned this unit for 15 years, I only have 350 or so hours in the saddle. That's to say the hydraulic fluid in my tractor is 15 years old. I do plan to change it soon (as other maintenance items are due) but should hydraulic fluid also be changed at certain time intervals, regardless of engine usage?
 
   #2  

ljjhouser

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I don't know about oil breaking down over time and changing its properties. But I really would be concerned about moisture in the oil. I say that because a small amount of moisture could really effect the properties of oil, or maybe even create sludge. But even car manufacturers, on the new trucks have dash warning telling drivers when to change oil. Best Wishes, Larry
 
   #3  

crashz

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There are a lot of factors to oil changes. Engine oils are subject to combustion gases and can develop acidic components over time and operation. As Larry stated, moisture in a system can also create sludge, corrosion and is part of the acid build up. Engine oils have components that fight those properties, but eventually additives wear out over time, oversaturation or heat cycles. That's why its recommended to run an engine up to temp once in a while to burn off that moisture and also why short trips are so hard on an engine.

Oils that aren't subject to combustion have it easier, but moisture and contaminants are still a problem. Also extreme wear component that are often added to high-load components (axles and transmissions) do wear out over time as well.
 
   #4  

RalphVa

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Oil in original container will last indefinitely because it has not come in contact with anything to harm it.

Hydraulic oil, if you've never disconnected a coupling, should last the full 400 hours irregardless of time. Normal operation will likely warm it up enough to evaporate any water that is likely to condense in it.

Engine oil comes in contact with combustion blowby gases. They will degrade the oil over time, but I cannot believe enough in one year to require changing unless you do A LOT of short starts and stops (e.g. ones that will leave unevaporated moisture in the oil). I go multiple years on my Tacoma run only 1k/yr and now going multiple years on the tractor, generator and 2 cars. Will go by miles on cars and the 10 years on the generator and about 4 or 5 years on the Tacoma.
 
   #5  

arrow

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I did 4 engine oil changes in my JD 750 over the 28 yrs that I had it (Yanmar diesel) . I sold it in 2013 w 1650 hrs on it. Still running like a champ.
With roughly 60 hrs per year of use, I changed it around 400 hrs. Rotella 15/40.

Coinsides w what RalphVa is saying.
 
   #6  

Captain Dirty

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With all of the electronics in a modern vehicle there is a myriad of data available, time, engine RPM, ground speed, oil pressure and temperature, transmission oil temp, etc, etc, etc. The manufacturers have proprietary algorithms to use the data to tell the operator how much oil life is left and when to change the oil. While time spent at highway speeds is undoubtedly easier on the oil than stop and go and may be reflected by the algorithm, it is in the vehicle manufacturer's interest to change oil sooner rather than later. They would much rather point the finger at owner/operator error for failing to change oil than have the finger pointed at them for faulty bearings or other faults. No doubt time, be it engine hours or calendar date, trumps all else in the algorithm. To wit: Exactly a year to the day that I reset the maintenance clock, my pick-up sends messages "Engine oil life remaining 0%; Change engine oil soon".

What the electronics are unable to do, as yet, is chemically analyze the oil. Reputable oil laboratories will analyze a sample, compare the findings with prior samples from the same vehicles and compare them with averages for the same type of vehicle as well as make recommendations as to the remaining life. If results are unusual, their comments section will point to probable causes. To my way of thinking, the $30 or so per analysis for engine oil with low mileage for the year and for hydraulic oil that is not subject to the same stresses as engine oil is short money compared to the cost of an oil change and cheap peace of mind.
 
   #7  

Doughknob

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Didn't we just debate this a couple weeks ago?
 
   #8  

RalphVa

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I pose the question to those of you worried about water in your oil. Have you EVER changed it and it was milky, e.g. had water in it? Think not.
 
   #9  

Robin Veerman

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And I pose you a question. Have you ever noticed a white sludge on the inside of your oil cap? That is evidence of moisture in the engine internals, mostly during the colder seasons and especially with short trips on the vehicle...
However, Pretty common to see white milky oil in gear/trans oils though, as they hardly ever warm up like engine oil would, due to condensation or water egress due to worn shifter collars in tractors stored outside.
Dutchy
 
   #10  

RalphVa

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And I pose you a question. Have you ever noticed a white sludge on the inside of your oil cap? That is evidence of moisture in the engine internals, mostly during the colder seasons and especially with short trips on the vehicle...
However, Pretty common to see white milky oil in gear/trans oils though, as they hardly ever warm up like engine oil would, due to condensation or water egress due to worn shifter collars in tractors stored outside.
Dutchy
Yeah, there in cold weather. Doesn't mean it has gotten into the oil. I have never ever changed oil in anything: engine, trans, diff and found milky oil.
 
 
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