Why do high mileage oils have lower flash points?

[aquariuscsm]

I was looking at Pennzoil’s and Quaker State’s websites earlier. I was looking at the product data sheets for the Pennzoil Platinum high mileage and the new Quaker State full synthetic high mileage oils. The high mileage versions have lower flashpoints than their non-high mileage versions. Why is this? I would think it would be the other way around .

 

[OilUzer]

How significant are the differences?

iirc, HM oils are in general thicker and also have narrower band (xWy) and tend to have lower Noack ... which is a more important factor for hm than flash point.