'02 3.0i, 92k, burning quite a bit of oil now. Switch to 10w-40?

[TurnAround]

Starting around 56k my 3.0i started burning a bit of oil. Half a quart every 5k. That seemed somewhat within normal. Then around 65k it started burning more. A quart every 5k. I've always used 5w-40 (BMW recommended), and up to that point I was using BMW Castrol.

At that same time (65k) I had a discussion with my indi mechanic and did some posts on this board about a progressively higher and higher amount of yellow / gold paste sludge build up under the cap. The indi encouraged me to switch to Mobil 1 synthetic 5w-40. Many on this board did as well. The feeling here was that the Castrol did indeed lead to heavier sludge build up (iow, the normal accumulating condensation in the engine after shut off, wasn't then burning off very successfully on the next use).

I've been on Mobil 1 5w-40 since then, and up to my 92k now.

In the last few months I've noticed that I'm burning 1 quart of oil every one thousand miles. Umm.. that seems drastic. Not good.

I was thinking.. with those of you with higher mileage engines, have you switched to 10w-40? Would you recommend doing that?

But then also, I just did a search on the board here and I read a couple of posts that said do NOT use Mobil 1 because even though it says 5w-40 its actually still too thin by comparison to BMW's branded Castrol 5w-40. To the group here... do you agree with this? So like.. maybe the BMW Castrol rebranded thing isn't false after all?? I'm wondering, so maybe its indeed thicker, but also, that's the sludge build up cause as well.

Recommendations?

Thanks so much!