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Why wouldn't wiped out camshaft show in oil sample?

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I have a problem. I bought my 06 CAT ACERT with 420K miles. Now I have 680K on the engine. It didn't have any oil consumption when I bought it, so when I put my OPS Eco-pure on it, I put in full synthetic mobil delvac 1 esp. I did regular Polaris Lab samples every 20K miles, it had high Oxidation and Nitration from the beginning and base was dropping down quickly, so I never let the oil in longer more then 60K, I was refreshing the oil by draining few gallons with every filter change. But no wear metals signs. After they changed their formula for Nitration and Oxidation, my oil samples were good, now I have 143K without an oil change and level 0 on Polaris oil sample (please see pic of oil sample report). But I started to experience an engine vibration when pulling hard hills coming from the engine, so since I had my overhead done when I bought it 260K ago, I pulled into my mechanics so they can run it again. My mechanic took it apart and found wiped out camshaft and all rockers. Really disappointed, cuz he blames everything on full synthetic oil. I would like to hear some thoughts. I'm gonna replace the camshaft, and all rockers. He also found a broken ring on injector #1 what he says could be a vibration cause, but why wouldn't I get any fuel in my oil??? I always had less then <1 of fuel dilution. Do you guys think I should put mineral back in? or should go back to shorter oil change intervals???

Please see 2 picks of cam...

Any thought very appreciated... Thank you

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Faulty rockers can cause a cam to bite the dust. That happened to my ISX, and it NEVER showed on oil samples. Fortunately, found it out on annual overhead before it caused a major problem. Still was a bite in the wallet to replace a cam and all the rockers.

Your mechanic is not correct. The synthetic did not cause your problem. Sounds like the mechanics at my local Cummins shop who dumped in a heavy load of SCA's in my coolant because it showed no SCA when tested. That would be cool, but I was running ELC coolant that does not have SCA. What a bunch of idiots. I forced management to change out the entire coolant, and filter with fresh ELC. The mechanic's comment... "it won't hurt anything". They were still in the 1980's regarding coolant. Your mechanic is still in the 80's regarding synthetics. Just because they have years of experience turning a wrench does not mean they are up to speed on oils.

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to be honest with you...the camshaft is made from iron..and your iron went up steadly in your samples only dropping off on the last one..

syn oil did not cause this failure..IMHO improper valve adjustment did..

also IMHO the only place that opens anything in my engine is a CAT dealer shop..yes i know there are compentent mechanics out there..but going to a cat engine shop (not a truck dealer) gives you some recourse..and the cam looks bad and needs replacement but it was still running when u brought it in..

as for the broken ring on the injector...i may have been sealed and broke when it was removed..

hope this helps..

Update

oh i forgot to add..260k is IMHO far to long between overheads..once a year or every 150k is what my CAT shop recommends

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I can't tell why it doesn't show up in the sample but I had the same problem did oil sampling every 20,000 and wipe lobes right of the cam and never show any sign of a problem from the lab. I don't think the syn oil had anything do with your problem. I don't run syn engine oil any more couldn't justify the cost and seen no improvement in fuel mileage or longevity of the engine.

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My cam was wiped out cause of improper Harding of the camshaft so it was under warranty.

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the other guys are correct about the

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,,, my guess is that this is a : case, surface, tufftride, type hardening, and because it is not "thru" hardend once it goes through the depth of the process, it fails completely in short order .

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maek will be eternally grateful.
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