I bought a 2010 Prius IV with 115k miles back in June. Starting around late August, a warning light began appearing on the dash: "Low engine oil pressure." It usually pops up when cornering, beeps once, and then disappears after just a second. Concerned, I took the car to jiffy lube (probably not the best idea, but the only place that could get me in that day). They didn't know what to do so they just changed the oil, and it staved off further warning lights for a couple months, until late October when it appeared again with my friend in the car. She said we gotta go to walmart and get motor oil and top it off. We ended up pouring nearly 3 quarts into the engine. I put another quart or so in a month later, right around thanksgiving, and now the low engine oil pressure light is back (8 december)! I'm closing in on 123k miles (I drive a lot, about 320 miles a week: 160 down the mountain, and then 160 back up), and from what I've read, this seems like a pretty common problem for Prii at/around 130k. My parents are adamant I take the car to a *real* mechanic to figure out what's going on, which I will do, especially since I'm due for an oil change at 123k anyway, but I also wanted to ask the car-people what they think is going on so I can be informed when I go to the real mechanic. Basically: What is causing this? And what can I do to mitigate it? Thanks for y'all's input!
You may have a car that has more miles than it actually shows. Rolling back the mileage on these cars are becoming a common occurrence. In your situation,, it seems the engine is worn and is burning oil. It's actually pretty common for these 2010 cars to do this, but usually at much higher mileage. For now all you can do is check the oil level often and top up. The only fix is to get another engine.
For 2010 through to partway through 2014 (model years) Toyota specd piston rings with less outward springiness, to reduce friction, improve mpg (very slightly). Coupled with their 10,000 mile oil change spec, a lot owners of these cars have been seeing runaway oil consumption, starting anywhere 100k~200k. A new short block (around $2k USD for the assembly, not including labour to install) will have the revised piston rings. toyota did issue a technical service bulletin for this, including an oil consumption test. To weasel out though, you’d need to have runaway oil consumption (1 quart per 1100~1300 miles IIRC), with less than 60k miles on the odometer. Toyota for the win, I guess…
We can speculate all we want, but a real mechanic will need to diagnose the problem. It could be burning oil and need a rebuilt or new engine, or it could just have a nasty leak that you don't notice because it only leaks while you are driving. Either way your parents are right and you will need to take it to a mechanic to find out.
The oil warning is for low oil pressure, which occurs when there’s next to no oil left. Considering the protracted time, hill climbs, it’s a good possibility a new short block would be needed. A boroscope inspection of the combustion chamber (camera fed in via spark plug holes), by a competent mechanic, is a good first step.
He is certainly losing a quart every 1000 miles or worse which might have qualified for a free rebuild back in 2015 before the 5 year 60k mile powertrain warranty expired. A rebuilt engine is sadly needed and probably pretty quick before the head gasket leak shows itself. 3 to 1 it already has a head gasket leak but was temporarily masked with sealer. Some might check the oil at each fillup and top it off. You could buy the Costco 10 quart box for $40 which might last ten months a quart at a time. Oil is only a temporary solution as it is slowly clogging your expensive catalytic converter. Even an aftermarket bolt in replacement cat is around $2k. Best to rebuild the engine and get 100k-200k more miles out of it. A used engine is a crap shoot, but can be less money up front. Or sell it before other expensive items appear such as the hybrid battery and brake booster. Finally your engine repair options will vary widely with the most expensive fix generally at a dealer. See this link for the range of options. https://priuschat.com/threads/clean-everything-still-knock-when-pressing-on-gas-pedal.233358/page-2#post-3382766 In your case you need more than just a head gasket.
I just posted yesterday about a blown gasket in my 2011 Prius. Come to think of it, my Prius had the exact same issue as yours, about a year ago. The low oil pressure light would come on and beep every 3-4 months when it needed an oil change. The dealer blew it off, and said the issue was addressed with a new oil change. Fast forward a year or so, and here I am with a very heavy paperweight in my garage, and an insane bill from the dealer. You need to address this issue now. Good luck!
