UOA - what do they show?

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Had a look at the UOA on the LS1 at various mileage intervals. What is it showing? 1. The TBN is falling...what does this mean? How low can it go? 2. Wear metals are going up....what does this mean? How high can they go before it's unsafe? 3. Which number(s) show the point where the oil is breaking down and forming sludge? 4. Which number(s) account for the consumption ie. where's the oil going and what's happening to the left-over oil?
 
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TBN falling is the amount of the oil's additve package left. Below 2-4, the oil is at it's limits. Wear metals going up are exactly that, more wear as time goes on. Depends on the elements but on this one, Iron is getting high when it goes above 40. 3&4 I don't know. The experts will have to chime in. [Smile]
 
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3. If viscosity is out of spec oil is breaking down. Thinning would be due to shearing of VII, thickening would be oxidation. 4. I don't understand the question.
 
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This FAQ says that 100-200 PPM iron is acceptable...a lot of folks cringe at 20ppm. What's the deal? Matt [ June 19, 2003, 06:07 PM: Message edited by: Matt89 ]
 
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