I don't see the point of "needing" to run a high mileage oil just because it gets over 75k.
I have 150k+ on a 3.2L SOHC Isuzu engine, and I'll admit to running two rounds of Havoline high mileage oil in the last year, just for curiousity - truck is a long time straight Havoline 10w30 user for 140k miles.
I did like the HM 10w30 Havoline as it was close to a 40wt; but decided the truck really didn't need it as it never burns oil, doesn't leak, etc. and I didn't want to start any leaks by using an oil claimed to condition the seals.
Supposedly the conditioners are not supposed to cause leaks, but you just never know.
Recently, in the last 1k miles, my mechanic did a free oil/filter change and threw in Havoline blend 5w30, gotta tell you, I'm LOVING it!
I spent the majority of the summer under either 5w-40, 10w-40, or High mileage 10w30 (low 40wt) - which allowed a bit of drag on the engine.
I do a LOT of heavy mountain highway driving - living in Colorado, and I've heard a lot about xW-30wt's shearing to a 20wt under heavy use. And this truck has also seen it's share of idling, which also thins out the oil.
But I don't believe a Blend is as susceptable to shearing down as fast, so I'm sticking with the Havoline blend, 5w30 for winter, and 10w30 for summer - but only because I can NOT find ANY 5w30 blend anywhere!!
Truck has not used a drop and the idle smooths out faster in cold temps.