Today I had a weird hunch to check oil on my 2023 Prime and to my shock I saw what I have never seen before, milky oil on the dipstick and oil cap also covered in creamy oil. This is about the 5th time I checked the oil since new, once when brand new, once around 2k, once just before oil change, once after to see if overfilled, and now 2 months after the oil change. I will be going straight to the dealer first thing in the morning (on EV)
Is it possible you've been running the engine too little in cold temperatures and not allowing condensation to boil off? Lots of short trips in cold weather especially can result in this on an ICE Just a guess though, I'm too new to this to know for sure if that's a consideration or not.
Yeah if you've been doing a lot of short trips it could just be due to humidity. How's engine coolant level in reservoir?
Most of my driving is in between 7-15 miles. Start up in EV and drive, engine starts up automatically and shuts down automatically. I haven’t forced a shutdown after start up yet. It does its own cycle of startup and shutdown in EV mode.
It definitely seems like water in the oil. It's not catastrophic for the engine, but the best way to clear it up is to run the engine for an extended time to evaporate out the water. Take a trip to another city.
It's atmospheric condensation emulsifying with the oil. A longer drive with more engine-on time will boil the water out. This happens in lots of cars without anyone ever noticing. Congratulations on checking your oil more often than most!
Yeah if the EV portion is the majority, could be insufficient engine warm up. The rated EV range is 44 miles; you're getting that? Maybe purposely run it in hybrid mode, say once a week. Try that for a while before incurring diagnostic charges at dealership.
I’m in Toronto so it was pretty cold here a couple of weeks ago, I’m getting around 30-35 miles on EV. I do switch to HV about once a week and drive 7 miles with about 5 on the highway. I’m not too keen to drive with this oil so I will get the dealer to change oil and blame it on them . I mean I don’t see any mention about EV and HV operation and oil/water condensation in the manual.
I'd add to what others have posted above about driving with the engine running more often for longer times than you've posted you are currently running the engine, but only do that after changing the oil. If you can drive 100km with the engine on once or twice a month, that should be enough. Also, keep checking the oil after having it changed, too at least for the next 5k miles to make sure the oil doesn't get milky again.
No real need to worry an owner of a fairly new Gen 5 Prime w/ 5k miles on it of the possibility of a HG leak. With an older Gen 3 Prius, than maybe.
That's exactly why the OP should have the oil changed ( as his posts describe he plans to ) and keep checking the oil for a while to make sure. Than if it gets milky again, you can post that you told us so.
Yeah, unless he's losing coolant it's hard to call it a BHG. I've checked my oil once every other month and the coolant levels of both reservoir tanks as well. Nothing's changed except the color of the oil.
I checked and coolant looks fine, close to minimum line. The oil dipstick is showing about 2 inches over max.
Don't worry about HG yet. If you're taking to dealer for oil change, you can tell them about the coolant loss or not and see if they top it up like they are supposed to. Than keep monitoring the oil. I had milky oil at 5k miles with my 2014 PiP and dealer didn't check it at its 5k service, so I changed it myself and never had an issue with the oil after that, but I did watch the oil more closely after that to make sure.
I guess it’s weak spot of this type of engine design and lubrication system. But why incorporate a heat pump on top of it? Without a heat pump at low temps the engine would fire up often and prevent this problem.
Say what… are you for sure reading it right? Might help to pull it and wipe, then wait about 5 minutes before reinserting for the check (if oil is drawn up the tube this gives it time to drain back down). Also, the face of dipstick near towards front of car may be clearer.
It's not easy to read the Prime dip stick ( at least the Gen 4 Prime or maybe it's just mine that is so bad ). I've never seen another cars dip stick show full on one side and 1/4 to 1/2 quart low on the other side. And I still don't know for sure which side is the correct level. I just add 4 quarts + at change look at the stick and scratch my head, check it again, same thing ,.,.,.,.
