Recently acquired a 2006 Cayman S with 88,000 miles. I went through a PPI and bore inspection and everything passed. Driving it now for three weeks and oil indicator was at the lowest level. Added half a quart of oil next day after driving 20 miles it was back to low level. Added another half a quart and it is now full. Doesn't anyone else have erratic oil measurements or what could be the source of the problem?