My theory on why some Gen 2s consume more oil after 150k miles

Interesting theory......but likely only that.

It is perfectly normal for an engine to start using a bit of oil after 80K miles or so.
Usually the valve guide seals leak more than the rings and that is just plain old wear from use.

 

How do you explain the 2005 I have here that hasn't burn much oil since the last oil change at 153 miles? Dipstick still shows full. oil changed at 149k

 

Every engine is different. Even those that appear identical.
I did NOT say it was guaranteed........or even common for some models maybe.
I did say that it is not unusual, taking thousands of engines across the board.

 

I wasn't going to quote you, I just thought you may know something we didn't. Cause I'm trying to get to the bottom of why this oil burning occurs. There should be factors that cause it to do so. Jadziasman has his theory and I have mine.

Just thought you had your theory or insight to share.

 

Put the Prius oil burning in perspective: A Prius @ 200k miles burns less oil than many a NEW GM or VW.

 

I have and I did.
It really isn't a "theory" though.
It is:
1) Manufacturing tolerances
2) Simple wear. All moving engine parts wear during use, some more than others.
3) The luck of the draw. With a given engine that generally stays tight with high mileage and does
not typically show a large increase in oil usage.......there still will be a few that DO have increased usage.

In general, there is NOTHING you can do to "prevent" it from happening other than good maintenance practices.

Obsessing over things like this, over which you really have no control, is not good for your health.

 

double post

 

Yeah I've noticed that too jadziman. The traction battery and electrics cover pretty well for the relative lack of power of a 1.5L ICE in a 3500 lb car, but when really pushed in hills it does become apparent.

Also, many people have reported partial (but significant) loss of traction battery capacity over their years of ownership. For example, people have reported the traction battery fully draining (not really fully, but you know what I mean) when ascending certain large hills, where previously it didn't do so. Similarly with acceleration on a cold engine (another situation where the electrics cover heavily for the ICE), very many people have reported their older Prius's regularly "draining to pink" under these conditions, whereas previously it didn't. There may also be many more people with aging Prius's that are suffering this gradual in loss in capacity but not noticing it, because it's not so apparent with the particular routes/speeds they drive.

So yeah, the situation where a Prius might spend quite a lot of time revving hard like you describe could increase as the car ages, and it certainly may account for somewhat increased engine wear compared to a cars with a more powerful engine. I think your theory is definitely a possibility.

 

High Speed = High RPM = More Wear = Oil use .

 

This supposition implies that over the short interval that the car is now underpowered it incurs enough additional engine wear to leak. That would be equivalent to saying e.g., that a Yaris driven hard from the time it was new starts to leak oil when by the time it is 2 -3 years old.

 

2 or 3 years old? Don't get it, they are talking about long term use, at least 100,000 miles. The Yaris is under powered as well and could also be showing signs of oil use with age if driven hard.

 

I know what you're saying, most cars get driven hard from time to time. Let me say straight up that I don't think the Prius has a universal oil consumption problem, and that many (maybe even most) people will probably get long service life without having huge oil consumption problems. I'm just saying that I think there is a correlation between the size of the engine (and how hard it has to work) and it's longevity. So in this sense Jadziman's theory could explain why some Prius engines seem to burn increased amounts of oil at medium mileages where some other cars don't seem to do so as much.

 

I'd say: all else being equal, a smaller engine works harder and would have a shorter longevity.

Of course, everything else is far from equal. A good example is the Honda engines mentioned earlier. Lots of 1.5 and 1.6 Liter engines on the roads in the cities where they live a hard life, yet oil consumption is usually nil to not a worth a comment. So while we both agree that Prius ICE oil consumption is pretty minor in the larger picture, I'd look elsewhere for the reason.

Could a transition to higher revving more often unmask what until then had been a small, unoticed leak ? Sure. I presume that we have been reading the same anecdotes of engines starting to consume oil at a rate of about 0.5 - 1.0 Liter every 3 - 5000 km when the ICE hits 200 - 300k miles. Since there are just not that many cars with that many miles driven I am inclined to think the anecdotes will become a characteristic Prius finding. So far though I have not read of any engine analyses that pinpoint the cause. Have you ?

 

Most Honda engines have a higher RPM range then Toyota, so that would explain why Honda don't burn oil as much. But Toyota overall does not have an oil use issue. I believe its connected to hard driving. A friend of mine has a 2010 with 100,000 miles plus and is using oil. He knows he is the cause of the oil use, from hard driving up hills for miles at a time, every day.

 

If you google the new Honda 4 cylinder CRV and other cars of similar engine, you will find they have horrible oil burning too. I really believe the switch from 5w-30 oil to fuel saving 0w-20 has a major impact on this issue.

 

Synthetic oil also plays a part, much easier to leak through seals, and with age leaks are more likely.