Iron increase?

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47
I routinely measure ferrous iron in water systems. It is what I do for a living. I really hate trending ferrous iron in those systems because it really isn't an accurate measurement of corrosion rates. It can trend in that direction but there are too many other variables that can spike an iron reading. We use different chelant packages in different inhibitors and guess what? Some of them will hold more iron in solution than others. Your higher iron reading is often reflective of the product you are using to protect the system from corrosion so you have to know the product. The history of the system is critical because anything with corrosion in the form of iron oxide laying around in the system mixed with a strong chelant package will pick-up ferrous iron. It has nothing to do with current corrosion rates and anyone reading it as such would be mistaken.

So...I'm no expert on iron levels in the internal combustion engine but I am sceptical about trending iron readings and correlating it to engine wear.
 
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7,583
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North America
I have a 2020 Jeep Wrangler JLU 3.6 v6. I got my latest oil analysis back and iron has went from 16ppm to 28 ppm. Both intervals were around 5k with just over 200 miles difference. The other variables is late summer/Fall on the 16ppm and all winter for the 28 ppm sample and approximately 200 more miles. The other variable is I didn't drive my Jeep the last month before the 28 ppm sample. It would sit for days without being driven because I got car from my job to drive. My theory is that due to the days of sitting without running caused dry start up wear plus wear numbers trend up in colder weather? The rest of my numbers were spot on and nothing noted by Blackstone. Your theories?
Did you use the same oil for both intervals?
 
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18,185
Location
Upper Midwest
I routinely measure ferrous iron in water systems. It is what I do for a living. I really hate trending ferrous iron in those systems because it really isn't an accurate measurement of corrosion rates. It can trend in that direction but there are too many other variables that can spike an iron reading. We use different chelant packages in different inhibitors and guess what? Some of them will hold more iron in solution than others. Your higher iron reading is often reflective of the product you are using to protect the system from corrosion so you have to know the product. The history of the system is critical because anything with corrosion in the form of iron oxide laying around in the system mixed with a strong chelant package will pick-up ferrous iron. It has nothing to do with current corrosion rates and anyone reading it as such would be mistaken.

So...I'm no expert on iron levels in the internal combustion engine but I am sceptical about trending iron readings and correlating it to engine wear.
The two are not comparable. Water is a corrosive system whereas in an engine it is primarily mechanical wear unless the oil has a depleted TBN. But regardless of the origin, in your water testing you are using a chemical means to detect iron but in a UOA it is a physical means. For a UOA it makes no difference whether the iron is chelated or not since all compounds are decomposed in the ICP plasma. ICP cannot be fooled by the chemical composition of the tested element.
 
Messages
47
The two are not comparable. Water is a corrosive system whereas in an engine it is primarily mechanical wear unless the oil has a depleted TBN. But regardless of the origin, in your water testing you are using a chemical means to detect iron but in a UOA it is a physical means. For a UOA it makes no difference whether the iron is chelated or not since all compounds are decomposed in the ICP plasma. ICP cannot be fooled by the chemical composition of the tested element.
True.... I don't measure oxidized forms and the chelated ferrous is measured by the Hach method. But oxidized iron falls out of solution in either water or oil and you don't necessarily get a representative sample by pulling bulk oil. And you do have water in your engine because it is in the environment and it condenses inside the engine. The reason your TBN matters is because carbon steel corrosion rates vary with the alkalinity of the environment. I've not seen a study that shows what percentage of iron measured in an UOA is based upon engine wear vs. internal corrosion rates but corrosion rates never drop to zero, oil on the surfaces or not.
 
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35,970
Location
NY
I did not use the same oil for both OCI. One was Pennzoil Ultra Platinum and the other was Amsoil Signature Series. The engine has 14,823 miles on it
In all honesty aside from checking for coolant in the oil, fuel dilution, or a problem with air filtration, at 15K miles there isn't much else you'll get from a UOA. Engines can be shedding wear metals for 20K miles or more. Also in order to get an idea of how an oil is doing you should run the same brand of oil for at least two OCI's then sample. One OCI then switching brands really isn't a good idea for an accurate UOA representation of how an oil is doing. That's about all I'd be looking at in your UOA, until you log some more miles and use the same oil a few times.
 
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