Possible Oil Dilution In Skyactiv G (Yaris)

[TorchMini]

Our Family owns two Skyactiv G engines in the form of recent models of the 1.5 Liter Mazda engines found in the 2019 and 2020 Toyota Yaris compacts (formerly Yaris iA/Mazda2). They take the Toyota 0W-20, which I schedule for 5000 mile or 6 month intervals. [ Toyota is more encouraging toward 10,000 mile intervals as well as lifetime automatic transmission fluid, neither of which thrills me. We are making an effort to keep these cars on toward 200k miles each.]

My problem is that I noticed RISING OIL LEVELS on the dipstick of my 2019 Yaris, and when my wife bought a 2020 model, it was there again. Oil creeping up on the stick. [Level garage, checked in the morning quite carefully and repeatedly]

So I sent in an oil sample from my most recent service checks - one car at 35,000 miles the new one at 13,000 miles. By the time of the oil change they were both up several mm over the original top mark on the stick.

The reports showed- FUEL IN OIL at 2.0% after a 4000 mile interval, and a 'flashpoint' lowered correspondingly. All other oil parameters were normal, and the oil looked good.

I'm going to repeat the samplings at my next oil changes, which will now be aimed at 3000 mile intervals, until I know how well this diluted oil is treating my engines.
These are direct injection, 13-1 compression ratio engines, but they have good reliability and longevity records, as traced back through Mazda cousins.

What to do? Suggestions welcome! I will consider changing to a 5W-30, if the fuel continues to show in the crankcase oil, to adjust for this fuel-thinning effect. My Toyota dealer might balk at that on the 2020 Yaris which is still under warranty, but I'd do it on my 2019 car, to try to lower engine wear over time.

BTW- These cars don't get revved out too often. My 2019 does mostly mellow country roads between 30 and 55 mph with occasional town driving, while my wife's car is almost all short trips in town- which is challenging for the oil I know.

Any perspectives or advice would be appreciated.

 

[WobblyElvis]

Take the occasional longer trip. If your wife is always short tripping, swap cars with her once a week. The car will be fine.

 

[Imp4]

Why would 2% fuel in oil induce you to take any action at all?
What makes you think this would have any impact whatsoever on getting this car to 200k?
There will be a dozen or more repairs that you'll likely do on the journey to 200k and none of them will involve anything to do with an engine with the condition you describe.
BITOG strangely fetishizes fuel dilution and it almost never results in any negative outcome.

 

[BMWTurboDzl]

First you have to determine if 2% dilution is an issue. From what I've been able to gather it's not an issue until you get to 4% range. So just keep changing the oil, occasionally swapping car or maybe consider selling the car and buying an EV.

 

[billt460]

Why would 2% fuel in oil induce you to take any action at all?
What makes you think this would have any impact whatsoever on getting this car to 200k?

Because gasoline is NOT supposed to be getting into the crankcase.... In ANY amount. Fuel in the oil dilutes the lubrication ability of the motor oil.

 

[Imp4]

Because gasoline is NOT supposed to be getting into the crankcase.... In ANY amount. Fuel in the oil dilutes the lubrication ability of the motor oil.

And yet it occurs regularly across many makes and models.
Where are the piston/piston ring replacement threads?
And the rod bearing replacement threads, where are those?

Where are the rampant UOAs with 2% fuel dilution with high Al, Fe, and Pb numbers?

 

[PimTac]

Drive them more often and on longer trips. Take the long way to get where you want to be.

On the other hand we have seen many analysis reports with high fuel concentrations yet wear metals are fine.

Those SkyActiv motors like to run. Take them out for a good hour.

 

[billt460]

And yet it occurs regularly across many makes and models.
Where are the piston/piston ring replacement threads?
And the rod bearing replacement threads, where are those?

Where are the rampant UOAs with 2% fuel dilution with high Al, Fe, and Pb numbers?

It's happening because these engines are purposefully being designed with too loose fitting piston rings, in order to lower rotational resistance of the engine. All in an attempt to meet and exceed Federal CAFE mileage standards. Honda, Toyota, and Mazda, as well as other manufacturers are all having this happen. And raw fuel is blowing by the rings as a direct result.

And just because it's happening, and they're not doing anything about it, doesn't make it right. Toyota and Honda built nice tight engines for decades. Many, if not most, went 300,000 miles or more without ANY fuel dilution issues, or without burning a drop of oil. Now they're seeing fuel dilution issues in as little as 2,000 miles, with some engines showing well above a full quart over the full mark in that time.

Honda is dealing with excessive fuel dilution, while Toyota is dealing with seized piston rings that are gouging grooves into the cylinder walls. Both are caused by too loose fitting piston rings. Both are doing nothing about it, and are telling their customers both are "normal"..... They are NOT.

 

[spasm3]

Because gasoline is NOT supposed to be getting into the crankcase.... In ANY amount. Fuel in the oil dilutes the lubrication ability of the motor oil.

But I does. Probably due to high pressure DI spray when cold. And it used to be that way with carbs and iron blocks that warm up slow.
My approach is short oci 2k winter 3k summer, and 0w-40 oil in winter, xx-30 in summer .

 

[PimTac]

Because gasoline is NOT supposed to be getting into the crankcase.... In ANY amount. Fuel in the oil dilutes the lubrication ability of the motor oil.

Back in the days of carburetors gasoline would find its way into the crankcase, especially if you were the type to run around with the choke pulled open.

 

[Danh]

Why would 2% fuel in oil induce you to take any action at all?
What makes you think this would have any impact whatsoever on getting this car to 200k?
There will be a dozen or more repairs that you'll likely do on the journey to 200k and none of them will involve anything to do with an engine with the condition you describe.
BITOG strangely fetishizes fuel dilution and it almost never results in any negative outcome.

I suspect the OP’s 2% comes from a Blackstone analysis. And if Blackstone says it’s 2% it’s almost certainly much, much higher when measured properly with gas chromotography.

Outside of reversing the master/servant relationship with our automobiles and adopting different driving patterns there’s not a lot to be done, though going up an oil grade could be helpful: compensates for viscosity reduction and may (?) promote a better piston ring seal.

 

[ARCOgraphite]

My little ford has been having fuel dilution problems. A month ago, I took it for a 45 min interstate dr to visit a friend in Manchester. The next day coming from a car show in town, it got so hot I couldn't handle the hood prop rod.
When I checked the oil at the Irving Station, a quart had "disappeared" in two days. Oil was semi-translucent with black flakes dispersed in it.
I changed the oil and filter, but the Engine runs poor now at mid- higher rpm with terrible rattling racket.
Used to run smooth and velvety and powerful. At least that lasted from new to 4500 miles.

2.0 litre D.I. high compression high horsepower density.

Direct injection fuel dilution is a major issue on some brands, Do not attempt to minimise this significant and well reported problem.

I suppose a temporary solution would be to use the next grade higher to maintain a minimum safe oil film thickness.

or top off with this which has over 1% (10,000ppm) detergent and zdp package per sds.

Haven't tried it. Desperate times call for possibly silly desperate and futile measures?

Here is the sds .pdf

https://www.stp.com/sites/default/files/STP%C2%AE%20Synthetic%20Oil%20Treatment%20%282015-09%29.pdf

 

[BMWTurboDzl]

It's happening because these engines are purposefully being designed with too loose fitting piston rings, in order to lower rotational resistance of the engine. All in an attempt to meet and exceed Federal CAFE mileage standards. Honda, Toyota, and Mazda, as well as other manufacturers are all having this happen. And raw fuel is blowing by the rings as a direct result.

And just because it's happening, and they're not doing anything about it, doesn't make it right. Toyota and Honda built nice tight engines for decades. Many, if not most, went 300,000 miles or more without ANY fuel dilution issues, or without burning a drop of oil. Now they're seeing fuel dilution issues in as little as 2,000 miles, with some engines showing well above a full quart over the full mark in that time.

Honda is dealing with excessive fuel dilution, while Toyota is dealing with seized piston rings that are gouging grooves into the cylinder walls. Both are caused by too loose fitting piston rings. Both are doing nothing about it, and are telling their customers both are "normal"..... They are NOT.

Oil won't fix loose rings.

 

[billt460]

Oil won't fix loose rings.

I agree. Especially when the rings are loose by design. More frequent oil changes, as well as an increase in viscosity, will help minimize the amount of fuel in Honda crankcases. And will help keep deposits and gunk forming inside ring grooves of Toyota engines. But both are band aid "fixes" to a much bigger internal engine problem, that neither company wants to deal with.

 

[billt460]

I suspect the OP’s 2% comes from a Blackstone analysis. And if Blackstone says it’s 2% it’s almost certainly much, much higher when measured properly with gas chromotography.

Dam straight it's much higher than 2%. And you don't need, "gas chromotography". Just look at that dipstick on the Honda engine in the video I posted. You won't even see 2% fuel dilution on a dipstick. That dipstick is easily reading over a quart high. And remember, that is with his "oil life meter" on the dash showing 40% life left.

And for anyone who thinks it's not going to matter. Start dumping a quart of gasoline into your crankcase at every oil change. Then tell me in 100,000 miles how it, "didn't matter".

 

[ARCOgraphite]

Oil won't fix loose rings.

Loose how? Ring land clearance is specified so that comp gas pressure expands the ring and then combustion pressure provides the max sealing force. The static tension is a factor of ring height and depth and is minor factor in sealing, where taper and/or face radius shaping also effect oiling and sealing and stability

I am going out on a limb and postulate that with P.I you have hydrodynamic sealing from the wet fuel wash on the cyl walls during compression up-stroke.
This is a major factor you do not have in D.I at light to moderate throttle where the fuel is injected near the end of the stroke to cool the compressed charge. - Ken

 

[BMWTurboDzl]

Loose how? Ring land clearance is specified so that comp gas pressure expands the ring and then combustion pressure provides the max sealing force. The static tension is a factor of ring height and depth and is minor factor in sealing, where taper and/or face radius shaping also effect oiling and sealing and stability

I am going out on a limb and postulate that with P.I you have hydrodynamic sealing from the wet fuel wash on the cyl walls during compression up-stroke.
This is a major factor you do not have in D.I at light to moderate throttle where the fuel is injected near the end of the stroke to cool the compressed charge. - Ken

I was replying to billt460 who opined that Toyota and Honda engines were suffering from excessive wear due to their choice of rings. This choice also led to excessive fuel in the oil.

 

[ARCOgraphite]

I was replying to billt460 who opined that Toyota and Honda engines were suffering from excessive wear due to their choice of rings. This choice also led to excessive fuel in the oil.

I see that now. My apologies.

O.K. I direct my question to Billt460.

But Piston ring design is voodoo - like loudpeaker speaker design. Possibly a handful of those with truly great knowledge.
I will readily admit that am not one of them

But how bout my thoughts on fuel wash helping ring seal?

 

[BMWTurboDzl]

I see that now. My apologies.

O.K. I direct my question to Billt460.

But Piston ring design is voodoo - like loudpeaker speaker design. Possibly a handful of those with truly great knowledge.
I will readily admit that am not one of them

But how bout my thoughts on fuel wash helping ring seal?

Ya I have no idea, but I would think rings start to seal at combustion where initially there's a little blow-by at the very beginning of the power stroke. I don't think rings do much sealing on the compression stroke as oil is getting flung onto the cylinder walls as the piston travels upwards. My WAG.

 

[sohccammer427]

If you could do somewhat of a controlled experiment by trying to mimic the exact conditions but just changing one variable, being the oil to a 0w30 or even a 5w30, and while at it perhaps VW 504/507, it would be interesting to see what effect that would have. We'd have to count on the labs analysis to be accurate for both samples.