Oil Pressure Warning Light, Cold Weather, and Contaminated Oil

I believe I have a couple issues simultaneously with my 2007 prius with 200,800 miles. I recently posted a thread (Strange Red Triangle Behavior | PriusChat) that was mainly focused on issues related to a low charge on the 12 volt battery. But I think it is becoming clear that there are other issues now and I thought it might be worth starting a new thread focused on that. If I should continue on the old thread, I'm assuming an administrator will let me know and I can delete this one?

Here is the background info:

• The winters are very cold where I live. The last couple months have largely had lows in the negatives and we have probably had 20 nights in the -15 to -20 range.
• I drive the prius only on short trips on errands around town in the winter. For example, 5 minutes to the grocery store, then 5 minutes back etc. I can't remember taking a trip outside of town since November.
• After resolving the issues with the 12 volt battery by recharging it (no surprise that it got low given the 2 previous bullet points) the red triangle came on when my wife was driving it on a short errand along with the engine pressure warning light. I checked the oil and it was ~ an inch above the full mark.
• I last got the oil changed in June, and I have driven ~2000 miles since then. I did use the car for longer trips in the fall before the snow came, again very few of those miles have come in the last few months. I hate to admit it, but I don't regularly check the oil, so it is possible it has been overfilled this entire time. I put in Mobil 1 0W30 full synthetic oil.
• I drove it one other time before making it back to the oil change place, and the red triangle and engine pressure warning light briefly came on again and then turned off.
• The oil change place promptly pointed out that there is clearly moisture in the engine oil, whether water or coolant. He said it should be clear by smelling it, but he has lost his sense of smell since getting COVID. The dipstick had a distinct smell, but it didn't seem like the same smell has the coolant when I opened the radiator cap. I've attached a picture of the oil on the dipstick.
• The coolant was full below the radiator cap and the overflow both seemed full as well.

From responses at the end of my other thread, and from additional searching on the forum, it sounds like it could be (a) a head gasket issues and coolant getting into the oil, or (b) with the short range driving and very cold weather, possibly the accumulation of moisture that isn't getting burned off because the engine is getting hot enough.

I have an appointment with a shop in town in 3 weeks. Pretty much in line with (a) and (b) above I am trying to decide whether (a) to not drive it at all until they look at it which I assume would be the right choice if there is a head gasket issue or some serious engine problem like that, or (b) change the oil and drive it around and see what happens, which I assume would be a reasonable choice if it is just an accumulation of moisture from the cold weather and short trips.

I have also really been wondering if the oil shop overfilled it (yes, I will definitely be better about checking after an oil change, and checking in general for that matter) and it has been overfilled this whole time. Or with the accumulation of moisture and/or coolant getting into the oil, should it be that the oil level would increase by this much? Just curious.

Any thoughts or advice? Thanks for your time.

 

Yes, I would agree. It is certainly above the full mark. With the picture my hope was that the color of the oil might be enough for somebody to think it is moisture in the oil vs. coolant.

 

So once the low oil pressure warning lights happened, I stopped driving it for the two weeks until a shop in town could look at it this morning. They said that it does indeed look like there is coolant in the oil, and they did a block test and it was negative. They said there wasn't more that they could do and that I should take it to a toyota dealership. A few questions

1) Does it seem weird for there to be coolant in the oil but for the block test to come back negative?
2) Any other possible causes for coolant in the oil besides a head gasket issue?
3) Quite a few of you suggested testing the switch, if there is coolant in the oil I am imagining that it is no longer the switch that is the concern. Is that true?
4) There is a toyota dealership in a town 60 miles away. A couple of questions, since it is a 2007 prius with 208.000 miles, I have a feeling that it doesn't make sense cost-wise to try and fix it if it is a major engine issue like a head gasket. What do you think? If I do take it to the dealership, I'm imagining I should definitely get it towed rather than driving it the 60 miles right?

Thanks everybody!

 

Is there a pretty clear difference when the liquid in the oil is water vs. coolant? Just wondering since the shop said it was coolant. This is a generation 2 prius, is the head gasket failure usually coolant getting int the combustion chamber as well? And if so, does that ultimately lead to coolant in the oil?

 

I actually brought synthetic 0w30 to the oil shop from walmart, so I think this is unlikely.

 

Just to clarify, if it is indeed coolant in the oil, is the only way that occurs is something serious like the head gasket? Is it possible that it is a simpler seal or something that has gone out?

 

Any thoughts on whether it is worth, price-wise, considering replacing the head gasket on a 2007 prius with 208,000 miles. The hybrid battery is original as well...

 

So the shop that had looked at it and did the block test suggested that I could let the car sit over night and that the contaminant in the oil should settle to the bottom and then I could try to loosen the oil pan bolt to just let some out and hopefully see if it was water or coolant. I tried that, but the bolt started stripping a little and I couldn't get it off, so I just went to the oil change place to be safe.

I gave them a clear container and asked them to put some of the oil in it so I could try to let it settle. I have attached a picture of it, this is after 24 hours. Doesn't seem like anything has settled and it seems exceptionally dirty. Also, the oil on the dipstick, after the oil change, doesn't seem as clear as I would have expected. I have attached a picture of that as well. The oil shop said that the oil came out really slowly, and it was overfilled again! They suggested maybe there was ice in there taking up some volume?

A few questions

1) Any thoughts on the old oil in the first attachment? Does that look like water or coolant or just odd or normal for oil with ~2000 miles on it? I don't know how the oil shop got it. I imagine they have some exceptionally dirty oil pans and probably just poured it into the container from the pan after it came out of the car...

2) Does the oil on the dip stick seem less clear than would be expected for driving only 10 blocks after an oil change? Just wondering if the oil was really gunked up and would need to be flushed further to be starting from a clean slate.

3) The being overfilled again seems very odd. I believe the shop was careful in putting the correct amount in. Does this suggest there is some gunk in there? Could ice be a possibility? Again, it has been very cold the last 4 months and the car has only been driven on short trips, like 10 blocks here or there including driving to the oil place to get the oil changed. So if there was ice, I doubt it would have melted on the drive to the shop.

4) I double checked and the coolant is full as well as the reserve tank. Should I expect it to be getting lower if there is coolant getting into the engine? The coolant tank by the hybrid engine is slightly low, but this is a separate system right? Or is this the coolant that would be getting into the oil if there is a head gasket issue?