The only way to know what is going on with your oil is to run a sample.
I am running Shell Rotella T-6. If your oil is doing it's job of keeping soot in suspension it will be dark/black.
Bill
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2008 Newmar Mountain Aire
450 HP Cummins ISM 4000MH Allison Trans.
Towing a 2014 Honda CRV with a Blue Ox tow bar.
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