Oil Dilution

[Hybrid21]

I've noticed that over the last month or so my oil level has become slightly raised.

I do check my oil level on a regular basis so it is definitely raised from the full mark.

Over the last couple of months I have been doing mostly short journeys and the ICE has not really done a lot of work.

I was wondering what your thoughts on this would be and if anyone else has come across this phenomenon ?

[flash22]

A 2021 possibly has a GPF (Gas Particulate Filter) short journeys can be an issue

https://toyota-club.net/files/faq/19-09-10_faq_gpf_eng.htm

[Cyker]

Check under the oil filler cap - Is there any guck?

Short journeys can allow condensation to form and drip into the oil, but it'd be unusual for there to be some much that it's noticeable on the oil level, and you'd usually see an emulsion-like guck that normally gets mechanics rubbing their hands together just before they tell you the engine needs a new head gasket  

If it is condensation, just getting the engine good and hot on a run will get rid of most of it

How far above the full mark are we talking here anyway?

[TonyHSD]

Are you sure you are getting the correct readings? 
Can you park the car on a level ground and leave it for overnight.
In the morning first thing open bonnet and pull of the dipstick, place immediately horizontally and read the markings. Should at the max or near there, slightly above or below it’s not a problem. Touch the oil with bare fingers and squish it, viscosity check 😉, them smell it and try to find notes of petrol. If does smell a lot of petrol and it is very watery might be indeed diluted with petrol from cold engine work. If this is the case best to do an early oil and filter change. 
I remember last service you had share the mechanics did overfilled worth oil and you did take out a bit 500ml? If you still have it and you can take out some now and perhaps send for laboratory analysis. And if proof to be very different and mixed with fuel then might be someone to worry about, but I doubt it. 

[Hybrid21]

thanks guys, I'll monitor it and try and get a long trip in to heat it up properly.

Will keep you informed 👍

[Hybrid21]

19 hours ago, Cyker said:

Check under the oil filler cap - Is there any guck?

Short journeys can allow condensation to form and drip into the oil, but it'd be unusual for there to be some much that it's noticeable on the oil level, and you'd usually see an emulsion-like guck that normally gets mechanics rubbing their hands together just before they tell you the engine needs a new head gasket  

If it is condensation, just getting the engine good and hot on a run will get rid of most of it

How far above the full mark are we talking here anyway?

Raised about 2mm Cyker.

[kucyk]

1 hour ago, Hybrid21 said:

Raised about 2mm Cyker.

You are fine, but if I were you, I'd take the car for a longer drive and use the ICE, preferably on the highway.

[Cyker]

2 hours ago, Hybrid21 said:

Raised about 2mm Cyker.

Hmm, for that I wouldn't worry too much; Mine seems to fluctuate a little up and down by about that much too; When I first had it, I noticed the oil level dropped a tiny bit, so topped it up, but then it was back up over the full mark next time I checked it; If I had just left it it probably would have been at the full mark rather than over it  

I wonder if there is some sort of chamber somewhere that opens and closes or expands/contracts...?

[ernieb]

If the car was not exactly level it might well show a change in oil level.

I’ve had exactly the same issue @Cyker had above. Thought the level was low, topped it up and then it was over the full mark.  

[Hybrid21]

I've been doing a bit of research into oil dilution, especially in Toyota hybrids.

Seemingly quite common in vehicles doing short journeys where the petrol engine does not get a chance to reach it's full temperature due to a combination of the short journey, the electric power kicking in frequently and port injection.

The petrol slips between the piston rings of the cold engine into the oil in the sump. Apparently Toyota are aware of this and say that provided the vehicle is serviced as per the service schedule it will not cause any problems.

Personally I'm not really happy with this phenomenon 😕

 

[Mjolinor]

Unfortunately it is something that all IC engines suffer from with current technology. Once we get to ceramic pistons and blocks it will be fixed but I am not sure that will ever happen with this drive for everyone to drive modified dodgem cars.

[TonyHSD]

16 minutes ago, Hybrid21 said:

I've been doing a bit of research into oil dilution, especially in Toyota hybrids.

Seemingly quite common in vehicles doing short journeys where the petrol engine does not get a chance to reach it's full temperature due to a combination of the short journey, the electric power kicking in frequently and port injection.

The petrol slips between the piston rings of the cold engine into the oil in the sump. Apparently Toyota are aware of this and say that provided the vehicle is serviced as per the service schedule it will not cause any problems.

Personally I'm not really happy with this phenomenon 😕

 

Hi, 

this is typical for all combustion engines. Some are more prone some are less but all will do it. This is the reason why most  car manufacturers recommend early oil changes on cars driven in specific areas and conditions, one of which is short trips with frequent stop start driving and cold climates. 
In this case it is important if the oil starts getting contaminated with fuel to be replaced earlier to prevent sludge and stuck piston rings that leads to unavoidable cylinder wall damage and excess oil consumption at later age. 
Excessive idle is another reason for this event. 
 

[Stivino]

Has anybody got any links to this phenomena?  I'd be really interested to read about it.

[Mjolinor]

Google is your friend:https://www.google.com/search?client=firefox-b-lm&q=oil+dilution+in+internal+combustion+engines

[Cyker]

I think it's not so much fuel getting in there but water (Fuel sneaking in is more a diesel problem; Petrol engines usually burn off their fuel pretty thoroughly unless they're running rich, e.g. turbocharged petrols).

A large chunk of exhaust gas is just plain old water, and it can condense in the crank case if the oil doesn't get hot enough, and even when it does get hot enough it takes a while for it to evaporate out. The water/steam also reacts with other exhaust and crankcase gasses to form acidic compounds which get dissolved in the oil, which is why good quality oil is important, as cheap oil tends to skimp on things like acidity regulators and lubricity enhancers.

 

[Stivino]

1 hour ago, Mjolinor said:

Google is your friend:https://www.google.com/search?client=firefox-b-lm&q=oil+dilution+in+internal+combustion+engines

Thanks for the link.  I notice that only one of the links in the first page of the search is from an accredited body i.e. S.A.E.  I didn't bother looking at any of the others.

[Stivino]

1 hour ago, Cyker said:

I think it's not so much fuel getting in there but water (Fuel sneaking in is more a diesel problem; Petrol engines usually burn off their fuel pretty thoroughly unless they're running rich, e.g. turbocharged petrols).

A large chunk of exhaust gas is just plain old water, and it can condense in the crank case if the oil doesn't get hot enough, and even when it does get hot enough it takes a while for it to evaporate out. The water/steam also reacts with other exhaust and crankcase gasses to form acidic compounds which get dissolved in the oil, which is why good quality oil is important, as cheap oil tends to skimp on things like acidity regulators and lubricity enhancers.

 

Total word salad.