The onboard service indicator will activate when maintenance is required. However, in my view, the intervals between services are too lengthy, which may lead to problems with the lower engine components and timing chains. No technician will provide oil changes at a lower cost than extra ones, and throughout the time I had my 640d, I performed an oil change every six months. Fortunately, I had the privilege of having friends who run a garage, allowing me to use their ramps and get oil at discounted trade pricing. I would not exceed a maximum duration of 12 months or a mileage of ten thousand miles, whichever occurs first, for leaving oil in the engine. At now, I own a recently designed M4 model, while my spouse owns a newly designed 118i model, both of which come with a BMW guarantee. This implies that we are obligated to get them serviced as needed, including regular oil changes at the halfway point. Consistently, I use an authentic filter and high-quality oil.
Thank you