Agggh! My Prius burning oil, what to do now?

Adding 2 qts @ 5k miles or checking the dipstick and adding a 1/2 qt every 1k miles doesn't change the fact that the OP's motor is consuming oil. If it was a leak at that rate, it would have a smokey/smelly engine bay. Also, the bottom engine bay cover would hold most of the evidence (for a while).

 

IMO, having a noticeably oily, smoky , or smelly engine bay depends on exactly where the leak is, and how it drips down. The worst smelling/smoking leaks are those dripping onto the exhaust manifold or any of the associated pipes. Bad, but not as bad as having side draft carburetors drip gasoline onto such components!
Agree that plastic under cladding could trap dripping oil for a while if it kind of pooled in a low spot. But if OP drops that section when doing oil changes, as Mendl suggests, then he should see some evidence of the accumulation. I used to park on a clean driveway and always look for the telltale oil slick underneath the engine bay.
A further trick is to park car with engine and transmission positioned over a clean sheet of cardboard, so that the next morning you can backup the car and examine any accumulations on the cardboard to see if it is coolant, transmission fluid, engine oil, or some combination. That way you also could get a rough idea of exactly where the fluid was dripping down , and try to track it back to the source.

 

Oil accumulating on the top of the engine underpanel tends to attract grit really fast, so what you'll see is a really grubby spot. If you try to wipe it's a tenacious tarry underneath.

 

if you're lucky, it was not filled properly and you're not burning any oil.

if you're unlucky, you drove 5,000 miles, two quarts low.

 

now we're getting somewhere. that's a lot of oil. tell her to slow down.

 

My wife's 07 just bit the big one. She drives over a small mountain pass everyday on her commute and she noticed the red triangle and a beep in the curves a few times last week. Then rod knocking and tapping noises that even she described as bad sounding. When she finally called me about it and got some oil in it, it was down somewhere around 3 quarts. My mechanic pulled the pan and did some disassembly to look at the crank and cam bearing and reported that the motor is done.
We always had oil changed at the dealer every 5-6K, but unfortunately we failed to check the oil at fill ups and assumed that oil consumption would come on gradually as in normal cars. But running itself dry between a single oil change, out of now where is a little nutty to me boys. I had randomly checked it over the years and it always looked fine. Car has 120K on it and we are seriously bummed. This is exactly what we bought this car to AVOID. Guess its on us though, can't say that we didn't know cars need oil. I really am impressed with the uselessness of the oil pressure "warning" system they came up with, however. It beeps when your engine is toast and the oil is way past any healthy level. Great design there Toyota.
I've been reading about this PCV valve and some tiny oil filter buried under the air filter which can accelerate oil consumption somehow. I'd love to hear more about how this works. My mechanic mentioned too, that other newer engines with low viscosity oil and ceramic coated pistons(?) are having some trouble with this too, Subaru, Audi and BMW as well as other Toyota models. Sounds to me like they haven't got things figured out all that well. Anybody need a parts Prius?

 

maybe it did come on gradually?

 

So, how much is the ICE engaged when you're driving? That's some serious oil loss.

 

she should have stopped right then and checked the oil. this is what one is supposed to do. quite an expensive lesson. i learned a few expensive lessons in my life too. live and learn.

 

^ Does it show a little oil can symbol too?

 

It's about equally as useful or useless as the oil-pressure idiot lights most cars have had since pressure gauges became scarce, circa 1955. It's not supposed to be an oil level gauge.

 

Well, I meant the OTHER non-highway driving.

 

I am used to monitoring oil pressure gauges in small aircraft and our 1996 Miata MX-5. My experience in aircraft is that the oil pressure gauge does decrease slightly as the oil level decreases by more than 1-2 quarts , but the decrease is small and you must be used to what is "normal " reading when it is absolutely full to see the difference.
I agree that a oil level indicator connected to a good in-cabin display would be far better. Look, can anyone just hook a liquid sensor to the bottom of the dipstick that connects to a dash light? If we cut the dipstick so that the lower end was just below the lower oil Mark, it would seem to me to be an effective low oil level indicator. Anyone have a spare dipstick I can start to experiment on?

 

Would that work? What happens to oil level in the sump when the engine's running? Maybe it gets a lot lower?

 

Mendel, I think it would at least work when parked in a level position for the first 6 seconds before the ICE starts. Once the ICE is running, there is probably oil droplets being slung all over the place, so the fluid detecting sensor would detect oil. But having a "low-oil-level" light illuminated at start up should give sufficient warning to CHECK THE BLOODY OIL and avoid catastrophic engine failure. Honestly, that is a check that should be routinely run by the ECU before it lights the "READY" light, but I digress.