AEB Engine, 150,000km, 10,000km since last oil change. I park on a slight slope at night and noticed a clacking noise upon starting which would disappear after a few seconds. I checked the oil and it was reading empty. I put about 2 litres in and it's slightly overfull. A few days later, I checked it again and it was reading empty. Put another 2L in it and it's showing just above full for now. No visible oil leaks around the engine bay or under the engine and it's not dripping oil. Exhaust looks ok. Coolant looks ok. Any ideas?

 

Two liters gone in a few days of driving, and no trace? See how long this latest two liters goes. I might check compression and take a look at the plugs for evidence of oil.

 

So it was a leaking oil filter. When I took it into Audi prior, the oil filter had been removed to replace a gasket and then the oil filter was put back on. It had scratches on it and looked like it was cosmetically damaged from taking it off and putting in on. Approx 12 months later, developed a significant leak. I first noticed it by when I started the engine on a slight slope, a clacking noise was evident for a few seconds. The oil temp never went above the normal spot. I'm just wondering if any damage could've been done to the engine while I was running with the oil leak from the filter. Also, the oil pressure warning light never came on while driving.