DB9 Top Gear Track
AO Silver Member
Join Date: Jan 2007
Location: United Kingdom
County: East Sussex
Had you burnt that amount of oil in 90 miles (min -> max on the dipstick is about 1 litre) surely there would have been obvious signs of smoke and the spark plugs would be covered in oil. Had it been escaping from gaskets or pipes the engine bay would have been covered in it.
Who knows, maybe there was a blockage that's now cleared following the oil change, maybe the oil's worked its way into the cooler.
Top it up again and go for another run, keep an eye on the rear-view mirror.
All the best