Possible Oil Dilution In Skyactiv G (Yaris)

Joined
Mar 30, 2015
Messages
9,022
Location
Lake Havasu City, Arizona
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?
Like you, that's above my pay grade. I do know that we've had good tight engines come from both Toyota and Honda in the past. And not every direct injection engine has fuel / oil dilution issues. And I also know that making engines rotate more freely greatly helps meet CAFE mileage requirements.

And the tighter a piston ring seals, the more rotational resistance that is going to generate with the crankshaft. These engineers have become victims of their own creation. And it's not something they can easily backpedal on to fix. So they do what they most always do..... They tell their customers, "It's "normal". When we all know, it isn't.
 
Joined
Nov 2, 2017
Messages
77
Location
Colorado
My son's newly purchased 2018 Yaris ia oil level is also high, but I'm hoping that is just due to the Dealership overfilling (crossed fingers). He does a 70 mile roundtrip highway run daily, so I will keep a eye on the level. Had him do a redline up a steep section of the highway this last week to maybe heatup and clean the intake valves.
 
Last edited:
Joined
Jun 4, 2003
Messages
1,372
Location
98245
...
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.
Those short trips will increase fuel dilution. Driving tip: at least occasionally, use the low gears, rev it up to use the full throttle and RPM range. These engines like that, so long as you wait until the engine is fully warmed up and do it smoothly.
 

FZ1

Joined
Feb 7, 2008
Messages
5,628
Location
Texas
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.
Agree with your shorter oci. Try a higher vis 0w20 or a high vis 5w20.
 
Joined
May 15, 2011
Messages
11
Location
UNITED STATES. Kansas
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.
You could possibly getting engine to operating temp and romp on it a little. Or run about 30 miles in a lower gear. This could possibly seat the piston rings a little. This may prevent fuel from seeping past the rings. Just a idea that doesn’t cost anything. Except a little fuel.
 

TorchMini

Thread starter
Joined
Nov 30, 2021
Messages
9
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.
That's why I'm here on this website about oil. I might have thought gasoline in oil would decrease lubrication quality and thus age the engine sooner. Also I've wondered if the oil level growing up over the full mark would violate the spirit of 'Do not overfill' your oil as seen in the car's manual. So far my only action is to stop short of the top mark on the stick at oil change time and then let the level climb up to the top rather than over it. Then to change at shorter intervals to give the inner metals a good chance at a long life.
 

TorchMini

Thread starter
Joined
Nov 30, 2021
Messages
9
You could possibly getting engine to operating temp and romp on it a little. Or run about 30 miles in a lower gear. This could possibly seat the piston rings a little. This may prevent fuel from seeping past the rings. Just a idea that doesn’t cost anything. Except a little fuel.
I do rev it out occasionally, and use Sport Mode out in the country to boost the action. I'm not sure if helps the dilution, or the valves stay clean, or what- but it makes the Yaris more fun :)
 
Joined
Jul 14, 2020
Messages
1,106
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.
Shouldn't be able to run anywhere near smoothly with the choke left partially closed (which is obviously what you meant when you said open). Lots of people did and still do drive around with engine problems and hope nothing happens, but most of these vehicles don't make it to 200k miles for whatever reason (accident, or other neglected areas needing repair etc). I don't have the data to prove it yet but my girlfriend's GDI Hyundai usually smells like gas in the oil and my carbureted Oldsmobile does not. I don't believe her car has a hope in hell of making it to 200k miles but it's not going to have to anyway. Nothing wrong with trying to limit the amount of fuel being in the oil.
 
Joined
Mar 30, 2015
Messages
9,022
Location
Lake Havasu City, Arizona
Another thing is, that running the oil temperature over 212 F for a lengthy period of time will help to minimize this. But who does this on a regular basis? Almost no one who commutes in short trip city driving in cold weather, ever gets their oil hot enough, long enough. Especially when you have an engine that is continually dumping raw fuel in the oil as a by product of it's design.

As an example. The R-2800 Pratt & Whitney Radial engine used in the P-47 Thunderbolt in World War II, actually had a fuel dilution switch for the oil, right on the instrument panel. This was a feature they installed on the aircraft, to help aid in starting the massive 2,000 H.P. 18 cylinder engine in the European Theater, in the frigid cold Winter months. (Remember, synthetic oil didn't exist back then). The high viscosity oil used in that engine got very thick in cold weather.

Part of that process involved running the engine after the dilution and starting procedure, with the large cowl flaps closed. Which purposefully increased the oil temperature hot enough, to evaporate off the fuel diluted in the oil before takeoff. These aircraft could not draw takeoff power until the oil temp reached a certain temperature for a certain period of time.... All designed to get rid of the fuel that was purposefully introduced into the oil to aid starting. As well as allowing it to thin out enough to easily reach vital engine parts at high RPM takeoff power settings.

Now compare that to your Mazda or Honda, putting along from stoplight to stoplight for 15 minutes. All while the engine keeps introducing more and more fuel into the crankcase. All while the oil temp never gets hot enough before it's shut down. It is continually fighting a losing battle.
 

pbm

Joined
Apr 19, 2004
Messages
9,308
Location
New York
Like you, that's above my pay grade. I do know that we've had good tight engines come from both Toyota and Honda in the past. And not every direct injection engine has fuel / oil dilution issues. And I also know that making engines rotate more freely greatly helps meet CAFE mileage requirements.

And the tighter a piston ring seals, the more rotational resistance that is going to generate with the crankshaft. These engineers have become victims of their own creation. And it's not something they can easily backpedal on to fix. So they do what they most always do..... They tell their customers, "It's "normal". When we all know, it isn't.
Those 'CAFE mileage requirements' save some gasoline.....but with (smart*) people changing their oil at much shorter intervals due to fuel dilution, some of that 'savings' is lost.

*Some people will continue with the same OCI's they always did before the advent of loose fitting rings and GDI.....time will tell if long term durability remains the same...I tend to doubt it will.
 
Joined
Mar 30, 2015
Messages
9,022
Location
Lake Havasu City, Arizona
Those 'CAFE mileage requirements' save some gasoline.....but with (smart*) people changing their oil at much shorter intervals due to fuel dilution, some of that 'savings' is lost.
It's ALL "lost", because it was never there to begin with. You have to understand CAFE requirements were never designed to save a single driver anything. They are designed to save a small amount, over millions of miles driven by an entire years production of vehicles. Slice one single vehicle out of the "pie", and it's not going to matter in the least.

And the smart people who are changing their oil more often, are doing so to save their engines. That, along with going to a higher viscosity oil to counteract the fuel dilution problem.

If they, (Toyota and Honda), were really concerned about saving their customers money, they wouldn't have designed their engines with too loose of rings to begin with. And never got away from building the nice, tight, long lasting engines they've become known for. But then they wouldn't have made CAFE standards in the first place. Now it's all become a big Catch 22.
 
Joined
Jul 10, 2012
Messages
7,218
Location
South Carolina
...

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.
I wouldnt do anything except I would stop getting UOAs on the oil. Toyota and Mazda are not turning out vehicles that blow up on the road.
Do oil changes as required, 5/30 oil is fine.

We have a Mazda Skyactive 2012. Never bothered with a UOA, why? In my case, direct injection alone will produce some fuel in the oil, throw in the highest compression mass produced engine in the world (at the time anyway) and I should expect some fuel in the oil. However it makes quite a topic on BITOG *LOL*
Car is reliable as heck.
Being we live in the almost south I do use 5/30 in my vehicles.

Its a great discussion for a forum but meaningless to the public driving these vechciels of which hundreds of thousands (if not more) of these engines are in.

Make sure when you check oil its the same temperature of whatever you are comparing it too. Oil level will be lower when cold, higher when hot. You wouldnt notice (no way) 2% fuel but you WILL (VERY, VERY) possibly notice the difference between hot and cold. Long flat oil pan not as much, short deep pan VERY much difference when hot.

Your vehicles have no problems, enjoy them, change oil as recommended and your good to go.
 
Last edited:
Joined
Jul 10, 2012
Messages
7,218
Location
South Carolina
True, but are they turning out vehicles that will run 400K or more miles like they used to?
I guess time will tell.
Yeah, goes for any vehicle, just a 30 second search showed a Yaris with 2% fuel from 14 years ago. Doesnt matter, engine maker knows that.

Not sure if everyone knows Yaris last year of production is 2020
 
Joined
Jul 14, 2020
Messages
1,106
I wouldnt do anything except I would stop getting UOAs on the oil. Toyota and Mazda are not turning out vehicles that blow up on the road.
Do oil changes as required, 5/30 oil is fine.

We have a Mazda Skyactive 2012. Never bothered with a UOA, why? In my case, direct injection alone will produce some fuel in the oil, throw in the highest compression mass produced engine in the world (at the time anyway) and I should expect some fuel in the oil. However it makes quite a topic on BITOG *LOL*
Car is reliable as heck.
Being we live in the almost south I do use 5/30 in my vehicles.

Its a great discussion for a forum but meaningless to the public driving these vechciels of which hundreds of thousands (if not more) of these engines are in.

Make sure when you check oil its the same temperature of whatever you are comparing it too. Oil level will be lower when cold, higher when hot. You wouldnt notice (no way) 2% fuel but you WILL (VERY, VERY) possibly notice the difference between hot and cold. Long flat oil pan not as much, short deep pan VERY much difference when hot.

Your vehicles have no problems, enjoy them, change oil as recommended and your good to go.
I think the problem is this forum is divided by people who want to get the maximum life out of a vehicle (or at least think they do) and people that have no intention of keeping a vehicle beyond 10 years and 200k miles max. Will you give us some data on your 2012 in another 10-20 years at 300k miles plus?
My 2005 truck at 9504 hours would be at over 300k if it was all Highway driving. Currently it's 215k or so with lots of idling. It's a port injection ls engine so it's got lots going for it other than some leftover sludge from conventional oil at olm intervals the first 120k or so. I'm only following this thread because we also have in our driveway my fiancees grenade of a Hyundai 2.4 GDI that does short trips and gets fuel in the oil and my carbureted 46 year old Oldsmobile V8, that does some short tripping but no signs of fuel dilution. I plan to do some uoa's eventually because of my curiosity but I'm not pushing any oil changes to the limit. 2k on the Hyundai, 3k on the Oldsmobile, 4k on the Silverado (olm will hit 5k max, 4k in the winter usually).
 
Top