My friend has a 1996 960 with 340,000 km. The head was rebuilt 4 months ago. His son took the car on vacation and had the oil changed just before leaving with 10W-30. He drove 200 miles and parked the car for a week. His son checked the , thought it was low 2 liters - it wasn't- he just misread the dipstick, and overfilled it by 2 liters. He drove the car for several miles and noticed smoking from under he hood and warning lights were going off and on on the dash. He had it towed to a garage where they cleaned the flame trap, replaced a vacuum line? which was off and changed the oil to 15W-40. Car started fine, drove for 10 minutes but soon after getting to highway speed, he notices warning lights and smoke from under the hood. Car sat for 1 hour and started fine. Drove the car back to the garage and noticed a clicking sound, described as "slightly louder than a valve".

Car is still 200 miles from home and will be towed back in a few days. Does anyone have any thoughts as to what this overfilling would cause? Thanks for your thoughts.