The viscosity improvers used have had some history of gumming rings and such. So the wider viscosity range oils did have some issues in the past, but I don't know of that is true anymore.
Additives aside, actual breakdown is from oxidation of the oils, and non-synthetics will do that a lot faster than synthetics. And there are different oil qualities per brand. If you are really concerned about breakdown, my first move would be to use a known good quality oil. (Castrol has had a pretty good reputation for a lot of years.) A better move to reduce oxidation is to go to a synthetic.
As my anecdotal experience: I used to use Castrol GTX in all my rally engines. The oil would be really black after 300-400 miles of hard competition. I switched to Mobil1 synthetic and in the first event using it, the same engine that turned Castrol GTX black turned Mobil1 a slight brown. I was pretty impressed.
FWIW.....Most folks don't know this, but Mobil1 is actually petroleum oil. They refine the crap out of it to get the oil molecules to be almost totally uniform, rather than the normal mix of molecule sizes. That somehow gives it very different properties, like much less oxidation, higher film strength, and much better viscosity stability versus temperature.
