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Questions about 2007 Prius

Posted: Fri May 26, 2017 6:22 pm
by GerryAZ
I know there are a lot of Prius drivers on the forum so I hope you can help me. I have a friend who has a 2007 Prius that seems to be burning a lot of oil. I don't think it is leaking because there are no spots where it is parked. It only has 180k miles on it and the engine sounds fine, but I found it 3 quarts low on oil when I first checked it out. I just added another 3 quarts after it was driven less than 2k miles (mostly highway). Any possibilities such as crankcase ventilation issues that would be simple and inexpensive to check/repair? Is it possible that I am doing something wrong when checking the oil?

Thanks,

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 7:09 pm
by SageBrush
You will get much better advice on PriusChat.com...
The usual answer is that the friend let the engine run low on oil and overheat, and now has to deal with oil consumption.
Nothing to do to fix the problem short of an engine replacement, but he will have to learn to check the oil level frequently enough to avoid any more overheating episodes.

This is one of the downsides of small, Alu block engines: they are intolerant of abuse. I check the engine oil level* in my Prii once a month specifically to avoid this issue.

*Along with tyre pressures and the other fluids in the car. All in all, this takes me a good 5 -10 minutes a month. Most of the time is spent fiddling with tyre pressures, but I do that with the LEAF too ;-)

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 8:19 pm
by cwerdna
Basically what SageBrush said. Priuschat's the place to go and yeah, usually people let the oil run so low the oil pressure light comes on. By that point, the damage's been done (not necessarily overheating) and it will consume high amounts of oil until the engine's replaced.

3 quarts low is crazy.

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 8:40 pm
by LeftieBiker
The 1.8L Corolla engine used from '98 or so to 2002 or so has a terrible design flaw: if the oil isn't changed religiously and gets dirty, the tiny, single oil hole on each side of the piston(s) plugs, and from then on the car will burn amazing amounts of oil. I know, because my GF drives one. I was certain she had a high-rate, highway-only leak until I researched it. Toyota has a history of making oil passages so small that they only stay clear with strict oil change schedules and semi or full synthetic oil. In the case of that Prius, if the cylinders aren't scored from low oil pressure, one or more oil passages in the pistons may have also gotten plugged from dirty oil. IIRC, Toyota for some reason didn't recommend full synthetic oil in the earlier Priuses. They also tend to recommend oil weights that work great with new engines, but result in oil burning with higher mileage.

Long story short, a higher weight (10w-30 or higher) full synthetic oil might help.

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 9:32 pm
by GerryAZ
Thanks for the assistance. I did not want to register on Prius Chat just to ask one question. I was hoping there might be something easy like a plugged crankcase vent, but it sounds like the engine is toast. She said the oil light never came on so it must have had enough for the pump to circulate. I may try a fresh oil change with high quality 10W-30 or even 10W-40 since freezing cold starts are not an issue here in Phoenix.

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 10:05 pm
by LeftieBiker
If cold isn't an issue, then maybe 15W-50 full synthetic, if the 10W-30 helps just a little. I also can't say for sure that there isn't a plugged PCV valve in there somewhere.

A quick web search yielded this:

https://priuschat.com/threads/oil-consumption.97628/

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 10:39 pm
by SageBrush
LIghtly used engines are really cheap. If the friend can find inexpensive labor it may be worthwhile.

Re: Questions about 2007 Prius

Posted: Fri May 26, 2017 11:02 pm
by GerryAZ
Lots of information in the thread LeftieBiker linked. I will check PCV and recommend oil change with heavier oil followed by frequent dipstick checks.

Re: Questions about 2007 Prius

Posted: Sat May 27, 2017 7:38 pm
by sub3marathonman
GerryAZ wrote: a 2007 Prius that seems to be burning a lot of oil. I don't think it is leaking because there are no spots where it is parked. It only has 180k miles on it and the engine sounds fine,
(bold, italics added)

I think that's basically it. Even in the linked Priuschat thread, Patrick Wong, who is a very knowledgeable Prius enthusiast, stated, "t's not realistic to expect the engine to remain in as-new condition forever. 135K miles is heavy usage and would be near end of life for many automobiles." And this one has another 45K miles more.

It is almost certainly a valve issue, either the seals (85% chance), or the actual valves themselves (5% chance) as they are supposed to be set every 90K miles, and based on the owner's actions, I'm doubting that has been done. It is reaching, but IIRC there is a throttle body valve which might be sticking and needing cleaning, but I don't know what effect its improper operation would have on oil consumption. It is also remotely possible that the engine overheated and it is a head gasket problem, but that is unlikely too. In the old days, they'd take the head off and do a valve job, which would probably give this Prius another 180K miles before something else wears out.

One of the best experts is here on the forum now, Cor Vandewater, it might be worth sending him a message. There is also Hobbit, at Technofandom http://techno-fandom.org/~hobbit/ who is also extremely knowledgeable. Another person here is Cwerdna, others who were very knowledgeable and helpful have left the forums unfortunately in the intervening years.

Re: Questions about 2007 Prius

Posted: Sat May 27, 2017 7:40 pm
by sub3marathonman
GerryAZ wrote:Lots of information in the thread LeftieBiker linked. I will check PCV and recommend oil change with heavier oil followed by frequent dipstick checks.


I would hesitate to deviate from the Prius approved oil viscosity. I believe, but don't remember for certain, that you can do 10W-40 in the summer, but other than that you could be creating more problems than you're solving.