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I have personally installed two European imported Volkswagen diesel engines into cars here in the USA. Both engines were removed from wrecked, modern, maintained cars.
Removal of the oil pan on both engines showed excessive carbon and sludge build-up in the belly of the pan. Oil pick-up screens were both clean and filter housing were also clean. The deposits obviously form and settle out of suspension during the 130,000 KM which both engines had (approximately).
Based on my personal observation I would definitely change the oil at approximately 12,000 KM - 16,000 KM.
Those 30,000 KM drain intervals are not in the owners long-term interest.