Question : I OWN a German made exec car and oil change is only set at between 25,000km and 30,000km, depending on the chassis or engine models.
I have encountered sludge problems even though the mileage is still low compared with my other Japanese car which needs to be serviced every 10,000km maximum.
Both run on fully synthetic oil.
Is it due to our petrol quality or climate?
It seems that in four-season countries, there is no problem.
Sludge is usually caused by condensation in the oil pan or in more serious cases, water leaking from the block into the lubricating oil.
Maybe you are not using the car enough and all your runs are short and do not give the engine the opportunity to heat up the lubricating oil and remove any water condensation.
Try driving the car more and see if that reduces the problem.