Why is it that a car should be serviced, for example, every 10,000klms OR 6mths yet a bike only needs to be serviced every 8,000lkms? Why does the time between services not seem to be as important for a motorcycle?
Personally, when using dino oil, I'd change at 4,000kms / 12 months.
I'm now using full synthetic and will probably go the full 8,000kms.
Either way, I wouldn't leave oil change longer than 12 months. Shorter if riding in extreme conditions!
Burto.