... alleen aan het interieur moet ik wel even wennen.

We found patterns and driving habits that seem to effect this situation. Among them are track driven cars seem to rarely have this problem, or it happens at very high miles. 993's driven around town short trips, a/c on high all the time, seem to be more frequent. We have done an alarming amount of cars from Florida and Texas. We recently have done 4 cars with less than 50,000 miles on the odometer, two of them used a quart of oil every 1,000 miles. This oil consumption was thru the valve guides, our simple external cleaning would not work. The passages had to be drilled out because the carbon was so dense.