Our 2006 Prius never needed any supplementary oil in between regular maintenance (every 15,000 km) until we discovered about two liters missing at about 150,000 km. Since then (car now has 179,000 km), we have needed to add about a liter per 3-4,000 km. There are no oil spots on our driveway and the fuel efficiency is about the same as it was when it was new. Is this not unique? We reported this to our Toyota dealer when we brought it in for regular maintenance about 6000 km ago and they reported no problem. Since then, we've supplemented with two liters of oil. Thanks in advance for any insights!
This amount of oil use is not considered excessive at 112000 miles. Some excess ware would have taken place when the oil was let run low at 90,000 miles. I would just keep a check on the oil level "possibly each time you fill the fuel tank." This problem arises because people do not check the oil level on a regular basis. Over time any engine will begin to use oil, this is usually progressive. If the oil is not checked and runs low over several thousand miles maybe causing the oil pressure warning light to flash the damage is done. Using a thicker oil may help but this will be at the expense of fuel economy, so you may as well stay with the recommended grade. In short even though your car uses no oil check it on a regular basis after all how long does it take?
No that's not at all unique. From the reports we see here it's seem to be how it commonly happens. The primary problem is one of not checking the oil often enough. Losing 2L before even noticing is evidence of this. As the engine ages it starts to use a small amount of oil, but initially you may still go a full service interval without causing a problem. Eventually however you're going to get into the situation that you did, where you run the oil way below it's optimal level. Then you're running on perhaps one litre of very degraded oil, the contaminant concentration will increase and the low oil quantity may cause the oil temperature rise too. At this stage things can rapidly go from bad to worse. You probably got a fair bit more than normal engine wear during that particular event, so it's not really surprising that it now uses a bit more oil. All engines will gradually increase their oil consumption over the course of their lifetime. If you want this to be a smooth gradual increase instead of a quantum jump (like you experienced) then you need to make sure that you check the oil regularly and always top off before it losses more than 1/2 to 1 litre.
I don't know if this thread is also appropriate in your case: One for the Experts - Only (Oil usage) | PriusChat
