[AlanAZ]

How does the oil look when you open up the filler and scrap a drop onto a white piece of paper? Mine's a caramel color there by the time I change it, if it's black, be worried. If that's the case, run the next change for 500 mls and change again, filters too, to flush that crap out.

As a pre-caution, you might want to have an oil analysis done when you drop this oil. Blackstone Labs here in the States. Go to their website to order a kit.