Oil Consumption

A leakdown test is best, but no matter what, anything found by the time there is a problem, short of replacing (not cleaning, the springs get weak) the pcv will reduce the oil consumption short of a repair. I have never seen any lasting benefit to changing valve seals, because it is the guides that are the trouble. Changing seals with the engine together is not only extremely time consuming, but with no lasting result. At this point, the head should be pulled and reconditioned unless crankcase blowby is the issue. If it is due to stuck and not worn rings, after the head is out, the pistons and rings can be removed, cleaned, evaluated, and reinstalled or replaced. It is easier to do this in the car, because removing and replacing the engine is time consuming. The bearings in these don't go bad (again, unless the oil has been run down/out). Just make sure a quality, modern engine builder does this work. There are a lot of grocery getter shops that will make it last a couple more years, but the goal here should be to bring the engine back to factory specifications.

 

Tony2ltr
interesting, information, all makes sense to me
My situation
2009 with 238000 miles
Burning a qt +or- every 1000 miles,
Why.....didn't check oil and ran low SEVERAL TIMES, red triangle once
Had a severe missfire and hard hesitation - PLUGS SHOT 2 HAD SIGNIFICANT OIL ON THE THREADS AND 3 HAD BURNT OIL ON ELECTRODES-- replaced all the plugs (3rd set) runs better check engine light off on its own after 73 miles, check engine was multiple random missfire.
Gas mileage still poor 35mpg
Your thoughts made me wonder, original timing chain coupled with worn guides & misaligned valve seats & stuck oil rings could be big part of my issue
I just don't know where to begin with the fix.
I have abused this car, it owes me nothing - 2 minor accidents of others hitting me paid it off.....
But I want to drive it more....
I have built motors and replaced them, am willing too but with the other wear and tear it might just be best to drive it and add oil
Or
Do I replace the timing chain possible build the head, replace water pump at same time. I have the original accessory belts on it still
I do love this car
Don't chastise me for the oil, I am more aware than anyone I messed up
Thaks

 

First post, I thought I would chime in.

Recently came into a 2008 gen2 Prius. I've got 118k miles on it and so far no oil consumption to report (1.5k miles into a 5W-30 full synthetic oil change). I usually check my oil ever fill up just to keep an eye on things. The previous owner had it overfilled just slightly, but I don't think it's too much of an issue



The service history is a bit troubled. I'm yet to go through all of it to confirm that the oil changes were always done on time, but they were always done at a Toyota dealership- what troubles me is what they put in it. Some of the records say 5W-30, some say 0W-20, some say 5W-20.... Wth? You'd think a Toyota dealership would follow what is written in the owner's manual.

I've always worked on my own cars, so I'll be taking over the oil changes from here. I've been reading more and more about the oil consumption issues starting to pop up with these cars and it's a bit scary if I'm honest. I'm hoping these issues aren't nearly as common as reported on this board.

Before I got the Prius, I had a 2000 Acura TL with 220k miles on it before I got rid of it. Consumed no oil. After that, a 1999 Jeep Grand Cherokee with 141k miles, consumed no oil. Both of those engines were modern for their time (less so the I6 in the Jeep- that design is derived from AMC designs of the 1960s), but not necessarily by today's standards. (Even though Honda's J series V6 hasn't really changed much). All engines burn a little bit of oil naturally, but with Toyotas (and Hondas of the generation strangely enough- the oil consumption over on their boards is reported to be a lot higher), I think people believe they are unbreakable and therefore neglect the maintenance- skip an oil change or two and suddenly they're baffled as to why things start to trend down.

These are all assumptions of course.

I'm inclined to strongly agree with this post here. As to why people believe they are smarter than the engineers who designed the powertrain (and wrote the book about how to maintain it properly) is honestly beyond me.

Anyway, I thought I would hate this car and its actually a joy to drive, even for someone who is an automotive enthusiast and an engineer. Hopefully I can put many more miles on this car without running into this dreaded issue. I look forward to being a part of this community.

 

Yeah that looks like a dealer oil change. Extremely overfilled.

 

Btw do not check your oil at a fill up. It takes quite a while for all the oil in the head and the VVT actuator and the VVT filter to drain back. Check it at a fill up it will look low and if you top off then the stick will look like the picture u showed. Overfilled.

Check it first thing in the am before u start the car. That is the true level.

 

HPA, have you tried running thicker oil? A 15W-50 should still be able to start the car down to 20F, according to the user manual. This should reduce the oil use, especially if it's coming into the cylinders from worn piston rings. This will cost you a couple of percent in fuel economy, but will likely keep the car running longer. A qt every 1000 miles will likely clog the catalytic converter after not too much time. I would bet that thicker oil will at least half your oil use. A few members have also reported reducing oil use after running a few tanks of engine cleaner. I'd say it's probably worth the effort to try.

Otherwise it sounds like you won't be able to know the exact problem until you tear the engine apart. To me it sounds most likely like worn piston rings, but could certainly be valves as well.

 

One can purchase a new engine short block from Toyota. Also catalytic converter and its associated two sensors may need to be replaced due to heavy oil consumption.

 

At 75K miles my car starts to show some sign of burning oil:

2016-04-29: 64K miles, changed oil, filled to 4 mm below the "full" dot
2016-10-17: 69K miles, measured 14 mm below the full dot
2017-06-16: 75K miles, measured 25 mm below the full dot

I will change oil today.

 

It would be interesting to track the location of the oil consumption complaints to see if there is a correlation between cars in locations with cold winter conditions with those of us who live in perpetual summer. OMG, I love SoCal!

 

That's a lot of info, but there's a couple of things missing:

1. How far is it between the full and low dots on the dipstick?
2. What does that distance represent, in volume of oil?

#2 I can find readily, from the Owner's Manual:



And #1 I've circled. I went out and measured my third gen: it's 1.5 inch. Assuming second gen is the same, now it's possible to do the math:

1.5 inches representing 1.5 liters, is hard to resist. You've got a drop of 25 mm, so:



So, a liter in 11,000 miles, let's say roughly a quart every 10,000 miles. That's not trivial, but also not off the charts. Just keep checking it, top up instead of just letting it drop, and maybe a shorter interval: going 11K miles and not topping up will not help.

Noting also the dates: you've gone over a full year, and 11,000 miles without an oil change, not good. The Toyota Maintenance booklet says every 6 months or 5000 miles, whichever comes first:

 

I usually get an occasional puff of smoke after traveling down a hill and then stopping at the bottom and at the moment I press the gas to take off. It's embarrassing but when I bought my prius in 2014 from toyota, it already had 97,000 miles on it and I noticed a week into owning it that it lost 1 guard every 2,000 miles! Everyone I asked about it told me that it was common to lose that much oil in a prius. I was pissed but the car was mine already.

There is a campaign at toyota right now for certain engines that consume too much oil, if they determine that your engine is the one in the campaign, they will re-ring the engine at no cost to you. The camry engine and a couple scions with the same engine are in the campaign. They told me to keep checking back to see if my engine is included later on down the road. Doesn't hurt to give it a shot

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Thanks for filling in the missing info! Next time when I check oil I will measure the distance between the two dots. Toyota oil change schedule is very conservative. Used oil tests show no problems for my 1 year (about 10K miles) change schedule.

 

Forgot to mention the estimated loss of 1qt is about right judging from the amount of oil drained - just changed oil a few hours ago.

 

Distance between the two dots is 43 mm.

 

Spreadsheet presentation is not my strong suit, so hopefully you can puzzle out what's going on here:

Lower left rectangle is a ratio equation, considering your 25 mm drop, the 43 mm between the two marks, that 43 mm represents 1.6 quart drop, and accordingly your drop of 25 mm represents .93 quarts (yellow box).

Then:

Upper right rectangle is a second ratio equation, considering that your distance travelled was 11K miles, vs the standard US 10K mile interval. Bottom line:

You're burning about .85 US quarts (green box) per 10K miles. That's not bad at all.

 

Your killing me. Measuring what mm its from the full line and how much that is. Its alot of oil.

Why don't you just keep it at the full line?

Its a very small motor that only holds 3.5 quarts of oil so when its a quart low its probably more than a 35% loss of oil. Maybe more loss than that. Whats left in the pan after the valve/cam area and the VVT actuator vane and and VVT filter and the oil filter itself are pumped full of oil leaves little in the pan. Pan requires alot of oil. The highest component that needs splash lubrication is the piston cylinder walls and the rod wrist.
They'll be the first to suffer from lack of oil and it will scuff the cylinder wall and wear out the oil ring first as that ring is designed to move oil not run dry. If left to run real low the bottom end fails and it will begin to knock to alert you the motor is toast. Right around that time it will begin throwing non stop misfire codes from all the bottom end rumbling. The speed of the motor death is exacerbated by using crappy dino oil (dealer vat oil) because you can't run low on oil and have horrible quality oil to boot and not expect the motor not to blow up.

This is not rocket science keep the oil at the full line.

 

For once I agree with you: it's always better to keep it topped up. But he let it dropped, so we figured out his consumption rate.

 

The point was to quantify the oil usage. However, I'm in total agreement about keeping the oil at the F mark, there is precious little in there to start with, so in my mind letting it get less than 0.5 qt is too much oil loss.

 

Well in the old days there used to be advice on this forum not to fill to the full line; fill to 1/3 between full and low dots instead. I guess that's out of fashion now. Up to a year ago the used oil analysis reports were all good. I still yet to send in this year's sample.