Prius Prime cylinder wash-down potential issue

I agree, short trips are not the best for cars and engines. I had quite a few cars before the Prius... i'm 60 the Prius is the 7th brand new car i own, and i never had an experience like this before, i buy new car run it for more or less 5 years then change it for another new car. I was lucky i never had a car towed for a mechanical problem before. I take care of all my vehicles the best i can.

After more research i found something about that in the owner's manual.
Page 505 in the owner's manual it says "if the vehicle is repeatedly driven without the engine warmed up, moisture caused by drew condensation inside the engine or fuel wich did not burn mixes into the engine oil"

I am just disapointed with that weakness. I wish, i had known that before buying the car.

Pierre

 

The Outback has an oil temp gauge. In these Pennsylvania winter temps, the oil will only be at 100F after the 2 miles between home and the highway. That is still at the cold temp for oil testing.

My commute is 30 miles, plenty of time to warm up the oil to get rid of water. The person with the issue is commuting only 5km.

It is a weakness of all cars. Your past cars had more inefficient engines that kept enough water out to not trigger the oil pressure warning. The water could still be enough to be visible in the oil though.

 

my next question is: when the oil pressure warnigs pops up, is it too late to rule out any damage?

 

Another data point; 10 minutes at 35mph to 45 mph after start up in 39F weather, the oil was at 160F. It's a 2.5L with about the same oil capacity as the Prius.

In this case, the low pressure was because water reduced the viscosity to the point that the system didn't generate the in spec pressure. Unlike the case of low pressure from too little oil, there was the full volume of fluid flowing to all the parts. A water+oil mix isn't the best, but is still much better than no oil.

It would take an oil analysis of that water+oil to tell if there was excessive wear, and how much. Though if also one of the first oil fills for a new engine, some extra metal in the results is expected.

Then some water in the oil is expected, and won't cause an issue. Unless the oil level is also low, excessive levels of water will be visible on the dip stick before reaching the warning light stage. Short periods of engine use in a PHEV, and short trips with any car, means having to be more diligent in checking the oil, and even more frequent oil changes during the winter. Regular trips long enough to boil off the water from the oil will help, but if not possible, maybe look into an oil pan heater.

 

Yeahh they call me at the dealership where i work when it's time to explain to the customers what their clueless salespersons wasn't able to explain...

The oil turning to shit thingie isn't new. It's just more prevalent in hybrid cars due to the engine working part time. When the engine doesn't run continuously and has time to cool down, fuel and water get's trapped in the oil without any means to get out. Only 2 things can get water/gas out on the oil, enough heat for enough time to allow it to vaporize or an oil change..

Again that is the oil/gas/water mixture out of my 2024 Prius after a winter (01/24 to 04 or 05/24) of running in ev/hv mode.. NO CHARGE MODE! Note how it's brownish and cloudy like 2 differents paints are being mixed...



Now, that is the oil that came out of the same 2024 Prime 2 weeks ago with Charge mode used for 30km non stop every morning.. Mirror black and not cloudy, as it should be. It smells like well spent oil but almost no gas odour.




That's how you want to see old oil. To be honest, i think Mopar of all things nailed it with FORM (Fuel and Oil Refresh Management) on the 4xe Jeeps. My boss own a Chrysler dealership too and says it's rare that a hybrid Jeep has oil turned to Mayo because the computer will turn on FORM from time to time when it thinks it's needed and will run the engine until oil has reached X temp for Y amount of time. Neat..

 

Refer to my post above. Or PM me if you have questions. I live in Lévis so we could do it in french if you prefer.

Long story short. You didn't had problems with you ICE cars as they continuously ran so the engine had "enough" time to get the oil at least warm. Remote start for 5 or 10 minutes, a couples of stops and red lights and 5km.. the engine in a Prius will turn off every now and then in those conditions and wont get fully hot.. mine certainly don't anyway! Still a fantastic car but as with anything else, i'll give you something with one hand and i'll take something from you with the other one... in our case, out climate sucks..

A Mazda Skyactiv is a pretty impressive engine from an efficiency point of view and doesn't suffer from that same problem. The engine just needs some continuous runtime to vaporize crap out of the oil as with just any other engines. A Prius will ramdomly turn on and off (under about 65mph in my case) and won't get hot enough for that to happen.. nothing to do with efficiency... the most efficient engine in the world won't heat it's oil if it's on for 45 seconds at a time..

Not a flaw. More like user error and/or salesperson is clueless/doesn't know their products. My bet is scenario number 2... happens often. Condensation happens mostly in cold climates during winter. Doesn't happen during summer. Fuel dilution will happen if the engines barely gets hot (under 160°) as it need to get out of the fuel enrichment routine (cold start) for a decent amount of time. It will also happen if the injectors are dirty and the fuel atomization is compromized..

As i said guys. In CHARGE mode we trust. It's the only mode that will safely, CONTINUOUSLY run the engine whatever the conditions and ALLOW it to reach an OIL TEMPERATURE where GAS AND WATER can be vaporized.

Oil temperature is key. Oil can deal with a bit of water and fuel and it will vaporize if the engine reach full operating temperature. Once oil is saturated with gas and water, the only thing that will get it out is an oil change.

 

The Volt had maintenance modes to run the engine and burn off fuel if too much time spent in EV. I think even the PiP had one. It was assumed the gne4 Prime would have such, but I don't recall any reports of people seeing it.

A site I found in the old dial up days recommended oil changes based on the seasons because of temperatures and moisture. Three a year. One at the end of the fall and winter since that was when the most water will get in. Then the third at the end of summer.

 

Primes are programmed to burn the fuel if too much time pass without using it but nothing to prevent the oil from turning into mayo like Chrysler/Stellantis does with FORM..

Look at my highway morning commute in hv for example.. Starts the engine cold, runs pig rich for 2 minutes until the coolant warms up a little then 1 minute after having quit cold start enrishment mode, it just stopped... that was at 65MPH... then, it ran a couple of minutes, stopped, started again.. then stopped... no way the oil will get hot that way at -25°c..



The only way i had to force the engine into running for a bit longer when in hv mode was when i sped up to 70MPH. And even then it stopped sometimes...


I'll post a picture later on of the engine running in charge mode (battery will be under 80% when i'll return home so charge mode will be available.)

As for the oil changes based off seasons, the logic is sound but as much as the oil frequently gets up to temp you're not supposed to run into much problems IMHO. Never did it with the Civic and the good 'ol K24Z is fairly happy at over 300k miles. Doesn't burn much oil (a cup between OCI's) and there isn't a ounce of sludge in that engine.. i'll change the oils off some hybrids at the middle of winter though. More so if there are no Charge mode to engage to put some heat in there.. still, i consider my experiment a complete success!

 

Their concern wasn't just with the water getting into the oil, but what the water did once it got into the oil. When that happens, the water reacts with contaminants and degraded oil bits to form acids. That isn't a big deal as additives in the oil neutralize those, but they are getting used up doing so. Drying the oil out does not reverse that process.

Lower ambient temperatures means more water condensing in the crankcase, and those protective additives get used up quicker than during the warmer part of the year.

 

I understood what you meant and i totally agree. But i also think that, given the oil gets hot enough often, the importance is blown out of proportions. Hard to say without analysis, but "IF" the oil has a 8k miles lifespan in ideal conditions, both in engine runtime and climate, running the same oil in winter, might lower the lifespan to what? 7 or 7.5k.. That a 2cents guess that's not worth a damn anyway. Might be something to ask Lake Speed Jr. his opinion about..

Edit: For what it's worth, the Civic always made me change the oil earlier during winter then during summer. And contrary to those dummy milleage counter used by Mazda and Toyota, Honda's system decide when to change the oil based on temperature, load, fuel consumption, etc.. As i dont use the Civic as a daily drive since 2021, i don't quite remember the numbers exactly but i think 10k km was the absolute max i did during winter... near 20k was typical during summer. I also did a lot more trips during summer so it's skewing the numbers a fair bit..

 

As I said, it was an old report. Back when 5k mile changes were considered long, and more people were doing the 3K. What I recall was the writers basing the recommendation of reports of oil analysis and pH readings. It was more an argument against the 3k mile changes.

Today, it likely only apply to those driving lots of miles. Or PHEVs, as letting the water sit in the oil for longer periods could use up protective additives quicker, even with regular boiling off. Oil analysis is the only way to know for sure.

That makes sense if it operates like GM's oil monitoring system. That one monitors ambient temperatures in addition to the engine operating conditions. In an indirect way, it is accounting for extra water getting into the oil.

The Volt had separate maintenance modes for fuel and engine. Its oil monitor could go up to 2 years with low engine use. That could just be cautionary and the oil still good.

 

If you do not want the heat engine to start by unraveling the high voltage battery is more than 80%, just get on the neutral and brake mechanically. In addition, it is excellent to browse the brake discs.
To find out if the heat engine is hot, go to the energy control screen of the multimedia screen. When the engine is cold, it is blue and when hot, the color turns orange.

 

Problem is, it doesn't take a lot if time to warm up the coolant. 4 or 5 minutes will do the trick.. the engine oil however will take a lot more time.

 

Indeed, it takes a long time when the engine is orange to evaporate the water accumulated in the oil.