I've been going back and forth on this for a while now. My 2018 BMW 520i has the manufacturer recommended service interval of 15,000 km or once a year, but I keep hearing from enthusiasts that you should never go that long especially in this climate with all the stop and go driving. Then I read forums where people say modern synthetic oils are fine for 15k if you're using good quality stuff. I'm not tracking the car or anything, just daily driving to work and occasional highway trips to Dubai. I've been looking into an advanced engine care service that includes a full inspection rather than just dumping oil and changing a filter because I want someone to actually tell me if the engine is showing signs of sludge or wear between intervals. For those of you with similar European cars, are you sticking to the dealer's 15k schedule or doing 10k just for peace of mind? And have you actually seen any long term difference? Would love to hear from someone who's kept a car past 200k km on either schedule.