Depletion over time

[mjoekingz28]

What is it about time that 'wears' oil?

Do the contaminants, combustion by-products, condensation, and other criteria degrade motor oil as it sits?

I mean, take a 6000 mile OCI from a 6 month period then take another from 3 years on a fill. Of course frquency and duration of trips and weather temps and other factors can come into play.......but for studies' lets just focus on duration.

 

[mjoekingz28]

....example, a UOA of an oil that has sat unused (never started engine), verus, an oil that was used for 6 months, and then versus an oil that was in use for 3 years.





Is it like food going stale even though you dont use it.....like a cola unopened will last indefinately, then one that was opened and resealed will last a few days bit probably lose fizz, then one that was left out in the open will go flat in a few hours!!!!!

 

[Oldmoparguy1]

Originally Posted By: mjoekingz28
....example, a UOA of an oil that has sat unused (never started engine), verus, an oil that was used for 6 months, and then versus an oil that was in use for 3 years.





Is it like food going stale even though you dont use it.....like a cola unopened will last indefinately, then one that was opened and resealed will last a few days bit probably lose fizz, then one that was left out in the open will go flat in a few hours!!!!!

No...

 

[Leo99]

sealed cola has a finite shelf life. The taste fades away but the bubbles remain.

 

[snakyjake]

It isn't the "oil" that will wear out over time. It is the additives that will wear out over time.

One of the main additives is the anti-oxidants that will wear out after 1 year.

I've driven a few engines into the ground. Some with no oil change, some with no oil filter, some with very long oil change interval. The failures were never mechanical. The failures were in the rings, and the engine eventually consumed too much oil.

Therefore (for me) what I want is the oil and additives that can maximize the ring lifespan.

 

[Pontual]

Problem: 6k miles use makes some acidity and metalization and that's bad for a subsequent 3 years storage. Water, air, dust entrainment on top of that isnt good, too. Very slow oxidation takes place over time.

 

[turtlevette]

I have a fill of M1 15w50 in my jet boat that is 25 years old. If someone wants to pay for a test or do a test, I'll pull a sample.

 

[mjoekingz28]

Thank you for the answer snakyjake!


Thanks for the input Pontual

 

[Pontual]

Right.

 

[MolaKule]

The additives don't deplete.

Additives are compounds of various chemicals.

Due to heat and oxidation, the Chemical Compounds disassociates and become less effective.

The detergent compounds, which establish the basicity or TBN, are eventually overtaken by acids. This is why your TBN drops towards the useful life of the oil.


Quote:
_________________________
Originally Posted By: Shannow
Pontual is correct



Quote:
Originally Posted By: MolaKule

I agree with Shannow. grin2



I said I agreed with Shannow, not Pontual

 

[kschachn]

Originally Posted By: mjoekingz28
Is it like food going stale even though you dont use it.....like a cola unopened will last indefinitely, then one that was opened and resealed will last a few days bit probably lose fizz, then one that was left out in the open will go flat in a few hours!!!!!


It's not at all like that. Nice try but motor oils are not like carbon dioxide dissolved in a water at greater than atmospheric partial pressure. That CO2 has no choice but to come out of solution unless it is contained.

You would have a closer analogy with the sugar dissolved in the water.

 

[SuperSalad]

Originally Posted By: snakyjake
It isn't the "oil" that will wear out over time. It is the additives that will wear out over time.

One of the main additives is the anti-oxidants that will wear out after 1 year.

I've driven a few engines into the ground. Some with no oil change, some with no oil filter, some with very long oil change interval. The failures were never mechanical. The failures were in the rings, and the engine eventually consumed too much oil.

Therefore (for me) what I want is the oil and additives that can maximize the ring lifespan.

But on that note, what are the anti-oxidants inhibiting the oxidation of? The oil and perhaps other functional additives. Oxidation is happening at all times whether the oxidation inhibitors are "absorbing" the effect or not and the base oil is not immune to this effect as long as their are unsaturated bonds. That is typically what would "go bad" with an oil just sitting in a non-running engine barring any other contamination.

 

[MolaKule]

Originally Posted By: snakyjake
It isn't the "oil" that will wear out over time. It is the additives that will wear out over time.

One of the main additives is the anti-oxidants that will wear out after 1 year.

The failures were never mechanical. The failures were in the rings, and the engine eventually consumed too much oil.


Therefore (for me) what I want is the oil and additives that can maximize the ring lifespan.


I was under the impression that piston rings were a mechanical component as much as the bearings, crankshaft, camshaft, timing chains, etc.

 

[mjoekingz28]

Maybe he means it isnt a moving part- but a 'moved' part.

Like the cam is spun by the crank and the cam moves the valves, but the rings are only along for the ride.

.??????

 

[old1]

OK, let me get this straight, If I open a fresh bottle of oil, pour it in my crankcase, and drive the car around the block then park it, that in one year the oil will be bad because the additives will be depleted? If so, how is it possible that I have read here that there are some cars that spec 2 year OCI ??

 

[SuperSalad]

Originally Posted By: old1
OK, let me get this straight, If I open a fresh bottle of oil, pour it in my crankcase, and drive the car around the block then park it, that in one year the oil will be bad because the additives will be depleted? If so, how is it possible that I have read here that there are some cars that spec 2 year OCI ??

It seems you've jumped to a conclusion that is not correct. What we are saying is that the additives are being "depleted" or their usefulness is being diminished over time. Over what length of time will vary depending on conditions. Things like heat, cold and moisture can accelerate that rate of decomposition or additive fallout, but one year or even two is not generally going to be an issue.

Unfortunately things like this are not so cut and dry, there are a lot of qualifiers and conditions that go into this sort of thing that will change the outcome.

 

[old1]

OK, good, because last year (summer months only) I drove my 65 mustang about 1000 miles, all 20 miles or more, all warm weather, easy highway driving, and I didn't change the oil last fall. It has been a relatively warm (above freezing) garage all winter. I was planning to use it about the same this summer before changing it this fall before putting it to bed for the winter probably in late october. It has 10w30 dino oil, and a fram ultra filter.

 

[MolaKule]

I think we need some clarification here.

Additives are not "depleted" but their usefulness is being diminished over time due to heat, moisture and oxidation.

Additives are compounds of individual molecules that disassociate and loose their effectiveness over time.

Drop out - additives are generally in "solution" in the base oils but may separate over time. Generally, warming and shaking usually remixes those components.

Depletion does not = Dropout.

 

[SuperSalad]

Originally Posted By: MolaKule
I think we need some clarification here.

Additives are not "depleted" but their usefulness is being diminished over time due to heat, moisture and oxidation.

Additives are compounds of individual molecules that disassociate and loose their effectiveness over time.

Drop out - additives are generally in "solution" in the base oils but may separate over time. Generally, warming and shaking usually remixes those components.

Depletion does not = Dropout.

To be clear, I was saying depletion and dropout as two separate things, but now that I look at the way I wrote it, I can see how it might look like I was saying that depletion and dropout are the same.

Low temperatures generally contribute to additive dropout and high temperatures and moisture generally contribute to additive diminishment.

 

[mjoekingz28]

Ok Gentlemen, slighty altered topic.

What in an oil, like those Barret Jackson (or whomever made a classic car oil) makes it suitable for long length of time drains with low mileage?

Take long length of time and compare it to Amsoil and Mobil1 EP that are still a year's oil but are high mileage.



So, what can keep collectors and restorers from draining virgin oil incessantly/constantly/repeatedly? They already have to worry about flat spotting tires and keeping the battery right.



Is there an oil that isnt high performance that will lubricate just okay for a cruise or two around town once in a while and stay in the sump for years?