Hmm. Oil weights...
Now, I'm usually the first to say "Just because someone tried it and nothing bad happened doesn't make it a good idea." -- or at least I'd want to say it.
In my NA, starting from about 100,000 km, and up until the 7M-GE came out of the car at 450,000 km, I ran 10W40 in the winter, and 20W50 in the summer. I liked the higher pressure on the gauge, made me feel better. In the end, the engine did use a lot of oil, but that was crunchy valve stem seals. I was looking for signs of blowby, but that seemed perfectly reasonable, so I felt that I wasn't having oiling issues.
Of course, I didn't do a teardown of the engine, so I can't tell you what the bearings looked like, though there was no signs of them being spun, nor of rod knock.
It was also an NA, which means no oil squirters, and no turbocharger to oil. This means that less flow is needed to get everything done. It's really a different system than a GTE.
Was it a bad idea? I had people tell me so, but I think that in this one case going with my driving habits and this specific engine, my odometer, if nothing else, seemed to bear me out as it working. Would it work as well for someone else? Maybe, maybe not.
In the current GTE, I'm running synthetic 10W30 summer, and 5W30 in the winter. I should probably just use the 5W30 all year, but old habits die hard.