Interpreting Oxidation Results

[himemsys]

When one has a virgin oxidation value to compare to on a UOA, at what point does the oxidation value become high enough that the oil is condemned?

Is there a certain percentage to follow?

Let's say virgin oxidation is 5. What used oxidation value would this oil be condemned at?

 

[Rand]

Is this an oil containing esters?

Usually Other causes would suggest condemning the oil before oxidation is a significant factor.

Maybe @MolaKule could weigh in.

 

[himemsys]

If the virgin value is known, then we'd have an idea of the ester content. I'm just curious if there's a standard way of interpreting oxidation increase with use.

 

[buster]

It's a good question. I always thought you look at oxidation in conjunction with KV 100. No more than one grade higher.

 

[cptbarkey]

Excellent question, there must be a few other datapoints to plot out that would determine. Eager for an expert answer

 

[himemsys]

Lake Speed says that for a typical mineral oil with a starting oxidation of 8-12, that when it hits 30-40 that is an indication that it hit the end of its life.


I'd still like a more thorough explanation. Such as, what if starting oxidation is 30? At what value would that oil's oxidation be too high?

@kschachn
@OVERKILL

 

[kschachn]

Tom NJ has posted quite a bit on this, in the link below and other posts.

Mobi Jet Oil - VOA

A Gulfstream Jet :) :cool:True and I have modified the original question to: What "terrestrial" global vehicle requires a 5 cSt@100C engine oil with only one base oil (POE) and three chemical components?

bobistheoilguy.com

 

[Hohn]

I suspect that by the time you see oxidation levels that high in a UOA, there's a good chance you've already got a significant amount of varnishing and such occurring in localized areas.

My concern isn't with how much oxidation is in a sample. Rather, my concern is with how much oxidation occurred in the ring pack, or in the overhead seals and guides, for example.

 

[OVERKILL]

Lake Speed says that for a typical mineral oil with a starting oxidation of 8-12, that when it hits 30-40 that is an indication that it hit the end of its life.


I'd still like a more thorough explanation. Such as, what if starting oxidation is 30? At what value would that oil's oxidation be too high?

@kschachn
@OVERKILL

That's why the focus should be on relative oxidation, not absolute. Esters of course raise the virgin oxidation number, so you need a VOA to understand how much it has actually increased.

 

[himemsys]

@fantastic linked me this page from Oil Analyzers in another thread:

https://www.oaitesting.com/reading-reports.aspx

According to this, they consider oxidation normal anywhere from baseline to baseline +17. So for an oil with a virgin oxidation of 10, a used sample in the range of 10-27 would be considered normal.

Baseline +20 would be "elevated"
Baseline +23 would be "abnormal"
Baseline +27 would be "critical"

 

[MolaKule]

...My concern isn't with how much oxidation is in a sample. Rather, my concern is with how much oxidation occurred in the ring pack, or in the overhead seals and guides, for example.

Bulk oil oxidation and TBN/Acid values compared to the new oil values would infer the degree of sludging and or coking within the ring pack, in addition to a compression/leak-down test of the cylinders.

I know of no test methodology that would determine oxidation of the oil in ring pack alone nor any method that could capture an oil or carbon sample for testing, since combustion is a dynamic process.