Keep in mind that the engine ticking is common place for these engines. However, with regular oil changes (rarely do I go up to 8k miles mostly 7k) and proper quality oils (like you mentioned) and engine cleaning (BMW manuel says gas /oil additives are not needed)... at the start of my ownership my 05 x3 I would use stp only during long trips. All this over time (I've had the 05 for going on 5 years) has got my engine humming! There is stronger additives out there (I've got some techtron somewhere) anyways keeping that oil topped off is a plus...truthfully you can hurt the engine with too little oil or exceeding the required amount of oil I go for 7 quarts.
Even tho the oil is euro (iv tried many brands) my x3 doesn't really favour mobile1 but really does like the German Pentosen brand and that was 5w 30 but that stuff is $40 bucks for the 5 liter jug. Can't afford that, well I probably could but the car is 14 years old.
Don't get too caught up in this subject.... many do see:
https://www.bimmerfest.com/forums/sh...php?p=13192341
https://www.bimmerfest.com/forums/sh...php?p=13076931
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