I'd be doing an oil change every 7.5k to 10k miles depends on style of driving and driving conditions, eg urban or motorway. The 335d had a oil change last year (7k miles ago) by Joe duffys and it will be getting a full service when i get back. The idrive is telling me I've something like 19k km if i remember correctly before an oil change is due!

Cost of oil and a filter is cheap compared to engines and ancillary parts, definitely wont do any harm :wink: