We had been just talking about Duron. Looks great on paper and appeared to work great in my ISB6.7.
I run the shp 10w30 year round up here on the prairies. I suppose one point of data to show its robustness, on my first sample, 24,000km, I had 2.87% fuel and the viscosity dropped from 12 to 11.47cSt. With some hard use and a decent shot of fuel, it barely sheared.
My second sample had 100 idle hours, a pile of cold starts and lots of short winter trips. While fuel was not traceable , viscosity was 11.57cSt.
Edit: after 24k the additive package was barely even used.