Wear metals are finally coming down now that my wife drives it 90% of the time mostly highway miles too. I guess I should stop treating it like a racecar.
I still drive it on the weekends. Check the out low insolubles with the tough guard. Also notable are the higher zinc here from my last SL Defy jug. I refilled with peak conventional 5w30 and the tough guard is the same filter will run it for another interval. I didn't get TBN this time because it's all highway miles and I know it's fine.