TSB on Excessive Oil Consumption for 2ZR-FXE Engine

They probably did it for countries where taxes are based on CO2 emissions.
Sometimes 1 or 2 grams of CO2/km less will mean a couple of thousands off the price. A few years back there was a change in how emissions are measured here in Europe and that had a huge impact on prices.

For example, we had a 2016 Ford C-Max which had a listprice of €35000. After 2018/2019 when they introduced the WLTP standard the price went up to €46000, that is over $50000 for a Ford C-Max.

Even a Corolla TS Hybrid that I currently drive. In 2019 that car cost €35000 and currently it is €40000 for the same version. This is all because the CO2 tax is being increased every year.

So if a manufacturer can shave off a couple of grams of CO2 it can make a difference of a car being a hit or being a miss. They go to great lengths to achieve that difference if they can.

 

Yeah, and we pay the price.

 

What do you think about the next 0w-8 oil that is already used in Yaris 3 cyl 1.5L engines. It has tons of molybdenum and borons to make the film strength as good as the 0w-20 at high temperature and speed. There is more Toyota burn oils during 5w-30 with non synthetic base oil like in 2007-2009 Camry, 1998-2002 corolla. Thinner oil is not the main cause. It is the piston rings design and extended engine oil intervals to 10 000 miles that many of us does not realise that it is only under normal conditions, no short trips, too much cold starts, towing, and extreem temperature like Canada.

 

IMO it just means that there aren't enough Prii with high mileage 2015 is still new.

The change they made they increased piston oil rings from 1.5mm to 2 which should increase their stiffness by 33% and would allow to make drain holes 78% bigger.. both should help to combat stuck oil ring issue but not much with heat induced geometry changes which is another common issue causing oil consumption and head gasket failure.

For those who:s researching this issue I was able to bring consumption from 1qt per 600mi to 1/3qt per 2000mi by doing repeated piston soak procedures. It doesn't seem to burn at least on first 3 cylinders, just on 4th one. Not surprising that one is usually runs hottest.

Google how-tos or lookup on youtube; the most effective method I found was repeated soak with CRC Intake valve cleaner (need to remove plugs) and running a quart of MMO in crankcase mixed with heavier oil 5w30 for a couple thousand miles. Use at own discretion YMMV.

 

Actually the oil consumption problem was showing up within three years on the 2010-2014s. Toyota started the production change in January of 2014.

Once the cylinder walls are scored no amount of soaks will help. The scoring is what allows the excessive oil consumption along with high blowby and all the downstream problems.

 

I haven't taken my engine apart but the ones I have seen had factory honing.. no ssidewall scoring. You have to get engine to a quart per tank and run it for a while to polish cylinders.. scoring isn't usually an issue.

Main cause of excessive oil consumption is use of low quality oils with lows flash point which creates carbon deposits around low tension oil rings and gets them stuck. Byproduct of switching to 0w20 oils.

The other issue is warping due to uneven cooling which seems to affect prius more because of stop and go.

Corolla (basically the same engine) had these problem since 2008 so switch wasn't Prius specific.

 

Right. 2013, revised head gasket
2014 revised piston
2015 revised piston ring
Yes, it is true 2015 is 1 year younger but it is much fewer problems. my dealership mechanics also told me the same story. Even with 150k miles or more 2015 or newer never have engine oil consumption problems. It includes Prius V and Corolla/Auris Hybrid outside NA too.

It is not because of 0W-20, but because of 10k miles interval that many are not eligible to do that. The quality of base oil in 0W-20 is generally better than most 5W-30 in the market. Not many 5W-30 is LonglifeIII certified, 506/507 with high TBN numbers. Toyota used Mobil1 API SN oil which is group III and IV PAO synthetic oil, higher flashing point than nonsynthetic 5W-30. The common problems in the past in Toyota engines were VVT sprocket wears out from the cold start, it is reduced by using 0W-16 or 0W-20. I still do not feel comfortable using 0W-20 on BMW or Subaru engines, but no problem on Prius or Land Cruiser.

Prius engines never get really hot, we barely ever need to replace the valve cover gasket even after 200k miles. Compared to V6 in Sienna or Camry that need valve cover gasket every 140k miles, everything is just mildly warm. Even the coolant temperature is generally only about 70-90C most of the time.

 

I think we're in violent agreement; for the most part.

PCV valve location on this engine has alot to-do with why oil consumption starts. Mine started consuming oil at about 220-230k.. I wasn't impressed to say the least.

As for running hot the issue isn't as much with running hot but with uneven heat distribution which amongst other things is causing head gasket leak. And they used thin wall inserts which combined with sudden temperature swing at restart can warp. If you look up part numbers the same yet Corolla never had head gasket problem because it doesn't go through multiple start/stop cycles

 

The main part of it is the design of the head gasket pre-2013. We can reduce the problems significantly by cleaning the EGR ports on the intake manifolds and the EGR pipes every 100k miles. If you do oil change interval 10k miles/1 year, you will most likely consume oil at about 200k miles because of carbon deposit over time in the cylinder rings. If it is not too late, less than 1 quart per 2000 miles, you can try engine flush products. Toyota dealers have them too. It is worth doing a boroscope check if there is no issue with the cylinder wall yet. . The best thing to do is do 5000 miles/6 months oil change interval, over time the high detergent of new oil eventually reduce the oil consumption. It is better to use the cheapest 0W-20 with ILSAC 6A certification and 5k miles intervals than the most expensive oil at 10k miles. There is a limit in chemistry on how to make stable oil.

 

I got impression that the quality of OEM PCV valve is lacking. At least mine after flushing gunk with brake cleaner sealed better than brand new replacement from dealer.

Yes new head gasket is better but old one wasn't an issue on Corolla. Never hear about blown one on them.

I had looked at bores with horoscope, the factory hone is still there so stuck oil rings were an issue. On 4th cylinder it must be the geometry, wear or overheating; steel rings are more sensitive to heat.

CRC intake valve cleaner has highest polyether amine concentration much higher than Techtron and it chemically breaks carbon deposits. Depending on deposits you may need several applications to break them down. Soaking pistons directly through spark plug hole is more effective than spraying in intake.

Some places are doing BG product flush if you want to go that route. Several CRC piston soak with running Marvel in crankcase did the trick for me, YMMV.

 

Corolla does not have so much on and off cycles that contract and relax the headgasket.
I believe soaking solvent from the sparkplugs holes may work better to unstick the piston rings and followed by 5000 miles oil change interval. Some people argue that using heavy duty diesel engine oil Mobil Delvac1 5w-30 may unstick the piston rings. I used it once in used car 2001 1.8 Corolla that have VVTI codes from sitting too long in dealer parking lot, after 2000 miles it disappeared by itself as the oil clean up the VVTI mechanism.