I guess you need to explain to me how Regens (DPF Cleaning) is getting soot into the crankcase, since the DPF is down stream in the exhaust system.
Now the older engines that Flooded the engine with raw fuel could result in fuel in the crankcase, but I fail to see how you're getting exhaust soot in there.
Now to the OP, I'm a firm believer in synthetic oil, but generally the first oil change and every oil change after. Not sure if it would be as great a benifit with your miles. Now if you live in the Cold North, synthetic is great for starting on those cold below zero mornings.