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.