2006 Prius using oil

It wasn't that many years ago (perhaps three decades?) when people were happy if their engine would reach 100K miles without needing major repair.

Now that your car has covered 140K miles, it is reasonable that the engine has experienced some wear which results in oil consumption. The easiest thing for you to do is to check the oil level periodically and add a quart at 1K mile intervals or whatever is needed.

The alternative is for you to replace the engine, which does not seem a cost-effective approach given the minor consumption you have noticed.

 

We'd like to help you pinpoint the cause, however, you'll need to provide more information than you have so far.

Some Prii have oil leaks at the timing chain cover - look around for leaks before you conclude the engine is using oil.

It has been established by many owners that the Prius will use more oil if the oil pan is overfilled or even if the oil level in the pan is at the full mark on the dipstick. It seems the crankshaft counterweights could be contacting (or nearly so) the oil as the crankshaft rotates above the pan if too much oil is present. Under these conditions, the crankshaft would tend to splash too much oil onto the cylinder walls, which is a bad thing since the oil control rings cannot handle excess oil very efficiently. If this was occurring some of this oil would get past the rings and get burned in the combustion chamber.

Another possibility is the PCV system is consuming oil.

To see if the PCV system is pulling oil into the intake manifold you'll need to remove the air filter and open the throttle plate to see if there is any engine oil pooled at the bottom of the intake manifold beneath the throttle plate - there shouldn't be any.

Also, try the following to see if your oil consumption decreases. You will need to watch the oil level closely however.

Instead of adding 3.9 qts to reach the full mark on the dipstick when you do an oil change, add only 3.25 qts. The oil level on the dipstick should end up close to halfway between the upper and lower marks (dimples). Next, drive 500 miles and recheck. If the consumption is partly related to what I've just described, the oil level should not drop as much as you've been experiencing recently. It might help if you switched to a full synthetic oil as a precaution as well if you do this because there won't be as much oil in the engine as you have been keeping in it.

Give it a try. As long as you remember to check the oil level after 500 miles you should be fine and you won't allow the level to drop too low if the consumption is caused by some other issue. If you're really cautious, check at the first time you refill the gas tank (which for me is usually about 325 miles depending on the season).

 

I checked under the throttle plate in our '06 today and saw some oil accumulated. There was enough that I could see the reflection of the flashlight and stick a screwdriver in it to verify that it was indeed oil. Same conditions as the OP: no oil consumption for 120-130K miles than all at once it jumped to 2-3 quarts between oil changes.

What's the next step? Replace the PCV valve? Where is it? I'm getting the aux. battery replaced this week (free labor at the dealership, heh heh); is this a DIY job or best left to the Prius Tech?

thanks,
Frank

 

I'm just curious what people class as a useful life of a disposable product; a car.

Should they last 5 years and 50k miles? 10 years, 100k miles or 30 years, 500k miles?

Mechanical parts wear out. Imagine what goes on inside an engine - hundreds of powerful explosions every second! Now it is meant to continue like this for decades with no wear? Nah. Anything past 100,000 miles is a bonus.

 

That used to be the case but these days 200-300K miles is not unusual, especially on a Prius. Materials science, manufacturing techniques and CAD tools have all led to increased reliability and performance. I doubt if there's any significant cylinder wear on this engine and would suspect (if anything other than the PCV) that perhaps valve seals were getting a bit used up. I fully expect the engine (and other components in this vehicle) to go 250K miles w/o major issues.

 

A sudden increase in oil consumption is often the result of a sticky PCV valve. Has the valve on your car ever been changed? It's on the car's maintenance schedule. At 120K it's way overdue.

 

I would approach it like this:
1. Visit a service facility and have them do a thorough inspection for any external leaks. At the same time you should have them change the PCV valve even if its working as preventitive maintenance.
2. If you want to test the internals of the cylinders valve seals etc... you can have a cylinder leak down test performed.

If the engine is leaking internally replace it or become religous about checking the oil level. We had a college student get by for over 2 years by topping off his fluid regularly in a Gen2 Prius that was burning oil before saving up enough to put a new motor in.

 

PCV is easily replaced as DIY - there are a few threads here - got the part at the dealer for <$10. You do have to remove wiper and take a few other items out of the way to get at the valve - but not a big job....