Excessive Oil Consuption Significantly Worse in 2010 Model?

No issues on my 2010 with 69k miles.

 

You have meddled with the primal forces of nature, Mr. Beale, and I won't have it!

A blanket statement (underlined in the quote above) supported by (as proved time and again in other "studies") is woefully inadequate.

Thousands and thousands of start-stop cycles can cause excessive wear of the "soft" bearing surfaces in an engine (such as the-lead tin-copper overlay on copper based linings of main bearings or on the copper-tin bushing in the pin bore of the connecting rod). It doesn't take much wear for an engine to start making objectionable noise or for it to begin consuming more oil than it should. Stop-start is a common durability test cycle. Many automakers use this test to assure that their components are capable of handling thousands of stop-starts without excessive wear.

Main bearings with alumimum-tin linings and polymer overlays are more wear resistant and bushingless pin bores in the small end of the conrod are also more wear resistant. I don't know what Toyota chose for the Gen 3 Prius but it's possible that the 1.8L has these upgraded components.

 

The contention or conventional wisdom that starting an engine causes wear on journal bearings is correct with "normal" engines. The Prius engine is NOT "normal".

First, there is no extra wear when stopping an engine. The oil is flowing right up to the point it reaches a very low RPM, there is no power being produced so the forces on the crankshaft are from it's mass and the piston/connecting rod mass. These are small compared to the power stroke forces. There is also a very good film of oil to protect the bearings.

When starting an engine the bearings are only protected by a thin film of oil left over from the last "stop". With a Prius engine this is sufficient because the engine is spun up to about 1200 RPM with no fuel being injected, so no power stroke forces, and the oil is flowing to the bearings before any fuel is injected. "Normal" engines start firing (power strokes) at very low RPM, typically below 500 RPM, where the oil pump isn't working properly. This is where bearing damage occurs. This does not happen in a Prius.

Yes, there is the possibility -some- bearing wear will occur. It is very small and has been shown at teardown to be less than "normal" engines over long term operation.

I say again, the Prius engine is NOT "hard working". It does rev up as necessary to produce requested power, just as, for example, a Corolla will rev up the same engine (with slightly different stroke) to achieve requested power. But the Prius NEVER applies load to its engine at RPMs below about 950 RPM. All other Toyotas do with this engine. They have to as they don't have MG2 to provide needed torque to get the engine up to the "power range" RPM.

 

Have an early 2010 - purchased in July 2009 - and no oil issues with 73k miles.

Do still have the ABS braking issues over bumps despite getting the recall done.

 

only toyota knows that for sure, but they will not tell. i'm pretty sure it's not the valve steam issue and the oil is lost through the rings. my guess it's a combination of 0W20 oil, long OCI, and low tension rings.

side effect of fuel efficiency. not a big deal of one checks the oil level. i understand most people don't.

 

you sound very authoritative on this, but very light on the evidence.

 

Equally or more important, 1200 RPM is (assuming appropriate bearing design and adequate oil viscosity) fast enough to maintain full-film hydrodynamic lubrication, meaning no metal-to-metal contact within the bearings.

 

Would this mean engine damage if the rpm is under 1000 rpm?

 

Not likely, at normal idle speed of any engine. At even lower speeds (starting and stopping), especially under load, the solid parts will make contact. Even so, normally very little wear occurs with good oil. Otherwise, bearing failure would be a common problem.

 

2010, 81k miles using Mobil 0w-20 full synthetic no oil consumption at all.

 

I have 73,500 miles on my Prius and the oil level drops less than 1/8" on the dipstick between 5,000 mile oil changes, which I consider normal. All engines use some oil during the normal course of operation and a little more as they age. I have gone back to 5,000 mile oil and filter changes because of excessive oil usage reports from owners with higher miles on their cars. These reports usually involve neglected or improper oil and filter changes; however, many are from owners who adhered to the 10,000 mile schedule. This would not be the first time Toyota prescribed too long of an oil change interval, i.e. 1987-1991 Camry oil gelling problem.

Edit: Corrected dates.

 

Back then, I believe the oil change interval was 7.5K miles for mineral oil (not synthetic). Since the problem was not reported in other geographic areas outside North America, I believe Toyota's view was that the oil gelling was primarily attributable to poor owner maintenance. Nevertheless, they settled the lawsuit and moved to 5K mile change intervals for the 2004 model year, with regards to Prius.

 

Case in point: maybe the next gen Prius maintenance schedule will have a transaxle fluid change interval, and they'll educate their service departments on it.

But then that would raise the thorny question: what took you so long?

 

Yep, that was the general scenario. I bought a new 1990 Camry XLE I-4, used the prescribed viscosity of Mobil 1 synthetic oil, Toyota filter, and changed the oil and filter every 3,000 miles. I had no oil excess oil consumption or oil gelling during the 16 years and 225,000 miles I owned it. It was also driven to high school and college by my son and daughter for 10 of those 16 years, at my (not their) expense, so it was driven hard. I say this to provide a real world example of how it pays off big time to use the correct oil and filter, and change the oil and filter at the proper interval. In this case, I extended the life and use of my 1990 Camry and avoided having to buy another car, which at that time would have cost around $18,000.

Maybe Toyota has erred again with the 10,000 mile interval, maybe not. However, it only costs me $30.00 to do an extra oil change each year to maintain a 5,000 mile interval. An extra Prius oil change per year for 16 years will cost me $480.00 vs. the $30,000 cost of a new Prius. Oil is still cheaper than steel.

Edit: It was actually a 1990, not 1999, Camry.

 

are you sure about it?
i'm aware about the 1997-2002 one: Toyota Agrees to Sludge Settlement for Consumers

 

I have a 2010 purchased in May 2009 with 198,000 miles. My Prius uses about 1 quart between oil changes at about 10,000 miles. I have noticed that if I do a lot of high speed highway driving for extended distances, (over 75 mph) it uses a little more oil. Note: at least half of my driving is highway driving.

 

A little over 100K miles, I do the oil and filter change myself w/ Mobil 1 0W20 every 5K miles. Doesn't use any oil.

 

It's been a long time so I am not sure about the exact dates of the oil gelling problem. I stated 1988-1991 because I recalled that as the time span for the Gen2 Camry. Looking it up, the Gen2 Camry actually spanned 1987-1991. Nonetheless, I think the oil gelling started in the Gen2 Camry and lasted quite a while because the 2.0L I-4 Camry engine and its successors and variants had the same basic design. I recall receiving a class action notice, but did not participate. The point is people who changed their oil more frequently than Toyota recommended were not afflicted by it; whereas, some people who followed Toyota's recommendation or went longer between oil changes developed gelling or sludge.

That said, I still occasionally see a Gen2 Camry on the road. It was one of the Toyota's best cars and served me well as described above.

 

That looks correct. I believe the problem occured mainly in that vintage (4rd generation) V6 Camrys.

My brother has a 1995 Avalon (same engine as V6 Camry) with well over 300K miles that has never consumed much oil. Two similar age (3rd generation) 4-cylinder Camrys in the family do like drinking oil---but were bought used, with unknown previous maintenance history.

 

Just wanted to add something to your diatribe. I've had an occasion or two where I overhauled an engine, from the ground up, and spent some careful time looking at all those journals on the crankshaft and such.

There's a point here: A working oil pump has an output pressure in the range of 60 psi or so. That high pressure oil is typically delivered directly to the main journal bearings. There's holes in the case that line up with holes in the journal bearings; that high pressure oil is then directly inserted into the miniscule gap between the journal bearing and the crankshaft itself.

In one car I worked on, if memory serves, the oil not only got into the crankshaft bearings that way, but it was also injected into more holes in the crankshaft, which took the oil up to the bearings where the piston rods were attached. (I believe that with most cars those piston rod bearings are lubricated by splashing around in the oil pan, so that engine may have been different.)

That high pressure oil flows up through channels into the head and is pushed directly into the camshaft bearings as well.

Finally: If one is running a mechanical pump, there is typically a piston-loaded-with-a-spring arrangement that gets shoved back with high pressure oil, allowing excess oil to squirt back into the oil pan, thus regulating the oil pressure. (Getting a stuck one of these is one of the paths to a blown head gasket, by the by, with ridiculously high pressure oil busting a hole in the gasket.)

Now, I've read physics articles where the film of oil inbetween the crankshaft and the bearing has been analyzed. When the crankshaft is turning, it's not quite centered in the bearing. The high pressure point gets a thinner layer of oil. However, there's a bead of oil ahead of the high pressure point that gets dragged into that thin area as the crankshaft spins, and that oil gets really pressurized in the process. But one doesn't get those high pressure points until the engine is actually burning fuel.

So, point #1: I don't know if the oil pump in a Prius is electric or not. If it's electric, the oil on the bearings is at high pressure and squirting madly in all directions before the engine starts spinning. If it's not electric, the engine is up to speed at 1200 rpm and that high-pressure-from-dragging film is in existence before the first spark plug fires. And, at 1200 rpm, the oil pump, electric or not, will be helping the whole process right along since the electric (if it exists) will be a full pump and the mechanical, if that's what's there, will be in its operating range. With the high pressure oil present at the journal bearing, the drag-the-film mechanism would be properly primed.

Point #2: Compare this to a conventional engine with a starter. I bet one is lucky if the engine rpm is higher than 20 rpm with the ignition firing immediately on a start-up. At that point there might be some oil in the bearings, but it's not going to be particularly pressurized, and the drag-the-oil-film-around-to-pressurize-it won't be working well, either, at low rpms. Hence: starting a normal engine leads to wear during the start.

Finally: Many, many moons ago I used to work in Naval Air. And, back in this day, there were a few Naval Aircraft on the ship (the COD in particular) that had a pair of those monster radial engines with the cylinders arranged in a big pancake around the propeller shaft. This thing did not have an oil pan, per se, but ran with what is known as a dry sump. Oil flying around inside the engine would head to whatever happened to be the low spot at the time (think: Flying inverted), would get sucked out of that spot and placed into a tank. Output of the tank would go through an oil pump, then the oil would be injected into various bearing surfaces and/or squirted at other bearings, like the piston rods.

When such a beast was started up, the first thing done was to pre-warm the oil in that tank; then start the oil pump; then an electric motor would spin the prop up pretty fast, and then the spark was turned on. All of this was done with the idea of reducing wear. Big, ridiculously high power piston engines naturally have more wear. Those engines are expensive and time-consuming to overhaul, so fewer overhauls are a Right Good thing.

So: I don't think the Prius suffers from much wear with the engine starting and stopping all the time. There are tricks to reduce wear, well known, and I'm sure Toyota wasn't sleeping when the did the engine on this thing.

KBeck