Just got my OA back from Oil Analyzers and looks like my oxidation is high. It was flagged and came in at 55cm usually it is around 30-35cm. Also this was the first sample that showed a higher than normal copper. Copper came in at 11ppm it is usually only 1-2ppm. Oil had 15,466 miles on it when sampled and was changed at the same time.

Any idea's about the oxidation, I figure the copper is from leaching from the oil cooler lines as my iron,lead and tin were all still low.

Here are my 2 last samples for the unit, approx 60k between the two.


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Could it be from the copper ? I thought I had read somewhere where larger amounts of copper could cause oxidation.

Could it be from the copper ? I thought I had read somewhere where larger amounts of copper could cause oxidation.

Could be, I am having the oil sampled again at my next change(15k) which will be @ 495K. So I will see how it is then. I know if there was antifreeze and/or water in the sample I would be a lot more concerned.

Oxidation is the measurement of the breakdown of the oil. It can be caused by elevated oil temps, increased soot or fuel loading, sometimes coolant contamination or extended drains.

Copper is either bearings or leachate from an oil cooler. Leachate happens only in new or recently replaced coolers. Once the oil additives "eat" the free copper the reading goes down and stays down unless the cooler is disturbed.

That said,

I wouldn't worry about the sample. Oxidation readings accuracy themselves can be affected by soot levels (yours was higher than before) and that can affect the machines spectrometer and give you an odd reading.

The copper....isn't high....I'd monitor it.

My take after reading through the numbers....during this oil change you worked the engine a bit harder than normal. The oil got abused a bit more because, your soot is up a bit, your TBN is down almost a full point, the copper could be from a thrust bearing (and with your mileage it wouldn't surprise me), your viscosity is up (from the soot) and winter is here (your sodium number goes up from road salt).

Oil Analyzers uses Polaris Labs to do their work, the way Polaris does Nitration and Oxidation tests is pretty wonky and the readings can be off on a single sample.

Like I said, I wouldn't worry about it, and if the copper is from the thrust bearing, it will take another 400,000 miles for it to become a "problem".

Oxidation is the measurement of the breakdown of the oil. It can be caused by elevated oil temps, increased soot or fuel loading, sometimes coolant contamination or extended drains.

Copper is either bearings or leachate from an oil cooler. Leachate happens only in new or recently replaced coolers. Once the oil additives "eat" the free copper the reading goes down and stays down unless the cooler is disturbed.

That said,

I wouldn't worry about the sample. Oxidation readings accuracy themselves can be affected by soot levels (yours was higher than before) and that can affect the machines spectrometer and give you an odd reading.

The copper....isn't high....I'd monitor it.

My take after reading through the numbers....during this oil change you worked the engine a bit harder than normal. The oil got abused a bit more because, your soot is up a bit, your TBN is down almost a full point, the copper could be from a thrust bearing (and with your mileage it wouldn't surprise me), your viscosity is up (from the soot) and winter is here (your sodium number goes up from road salt).

Oil Analyzers uses Polaris Labs to do their work, the way Polaris does Nitration and Oxidation tests is pretty wonky and the readings can be off on a single sample.

Like I said, I wouldn't worry about it, and if the copper is from the thrust bearing, it will take another 400,000 miles for it to become a "problem".

Thanks for the heads up. After looking at my trip log and thinking back at road/traffic conditions. You are correct since my last oil change I have been working the truck harder. Been cruising about 63mph instead of 58-60. Also looks like I have been in NYC and and lower CT. more also, which brings on a lot of stop and go. I always get uptight when something on the truck is not right/or changes. I will not be settled until I start getting OA's back that are within the normal ranges. So I will be testing every 15K to keep a eye on it.

You know if OAI. test for glycol?? I see where they test for water and assume if the water is really low(like it is in mine) then I shouldn't have any antifreeze leaking into the system. You would figure they would test for it, but I don't see it on the sheet.

You only cruise at 58-60 mph ?

I know Blackstone Labs shows water and coolant separate in my reports but it does not show oxidation.

You know if OAI. test for glycol?? I see where they test for water and assume if the water is really low(like it is in mine) then I shouldn't have any antifreeze leaking into the system. You would figure they would test for it, but I don't see it on the sheet.

Doesn't look like they have a specific glycol trigger, which is odd because Polaris does test for it...easier to watch your sodium and potassium....when they rise together coolant is starting to get in and they will show up first before a positive glycol result.

I hear ya on the speed....I've been doing a lot of 65 and need to get back down to 57!!

You only cruise at 58-60 mph ?
Not everybody gets to drive on highways with a 75mph speed limit (and practically no enforcement until 15+ over). ;)

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You only cruise at 58-60 mph ?

I know Blackstone Labs shows water and coolant separate in my reports but it does not show oxidation.

Yes unless I am in a hurry, then I run 63-65mph. Only go above 65 when passing someone. The highest speed limit up here is in ME. where it is 75 north of Bangor, but I don't see a need to run that fast unless passing someone or horsing around.:eek: