I pulled the very first oil sample on the 2015 EcoDiesel. I was very happy with the results. There's only 5,368 miles on the engine oil, but the oil spent 8 months in the engine. That's a lot of idle time, cold starts, daily short commutes, and some towing. The T6 lost approximately 50% of its TBN capacity as it dropped from 10.6 to 4.91, which isn't a surprise. T6 uses a softer base oil which doesn't hold up to oxidation like a better-quality oil, but it still protected the engine for this type of interval.
Oil Analysis Lab Test Results
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Blackstone knows that a thick 5W-30 still offers protection, but the oil has fallen out of spec. At 10,000 miles, you're running a 5W-30 oil. I wish Blackstone reported TBN and Oxidation values. My T6 cST was 13.4 and my TBN was 4.91 at my interval. Oil usually thickens as it ages, but sometimes fuel dilution thins it out. We'll see what your next report shows.
You must be doing annual oil changes.Well I really wanted to post my last oil analysis I mailed in early January but it was apparently the U.S. Post office didn't get it delivered! Dang it, now I gotta wait another year before it is time to change my oil again...
I drain oil into a clean container and keep the used oil until the lab has sent my analysis report. I figured if a mishap happens, as in your situation, then I could send another sample.
The EcoDiesel came factory with the 5W-30 spec, so I don't think viscosity dropping into the upper end of the SAE 30 range is bad. As we look at the major diesel oils (pictured below), they all drop into the SAE 30 range eventually. We've seen EcoDiesel owners running Rotella T6 for 25,000-mile intervals with no issues mentioned on their UOA report, although TBN was very low. I agree with @OhioTech that it is best to change oil when the TBN drops down low and viscosity starts to creep into the SAE 30 range, however, I think people like @OhioTech and myself take a more conservative approach to maintenance. It's quite possible there's still some good life in the engine oil.
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