2024 Hybrid 2.5 engine milkshake

[kbuchle2]

This thread encouraged me to go and look under the cap on my truck as well. I drive ~25 mins to work each way; we’ve had a cold winter here in Michigan this year. Oil changed last November, it probably has ~600 miles on it since then (was at the dealer for a fuel tank issue for about a month.)

When it’s cold out, if you’re running the heat while driving, the heater core pulls so much heat from the cooling system that by the time my drive is over, Im usually halfway warmed up, sometimes 3/4 on the gauge. Not running the heat will make the temp gauge stay higher, but when it’s 12 outside, thats easier said than done.

Other than running in sport mode (which I do sometimes, keeps the engine running unless at a stop light) there’s not much you can do to prevent this happening, unless you go out of your way to take a longer trip.

I’ve not checked under the cap in previous winters but Im sure mine looks like this here there throughout the season for the 4 years I’ve owned it. Wouldn’t think that it has anything to do with a blown head gasket/coolant getting in the system, just condensation from the temperature changes as well as water from the combustion cycle per some other comments in here. This is why the owners manual specifies a particular ford specification to stick to for oil changes, that oil is formulated to combat the long term effects from this.

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[HeyBales]

Oil/water emulsion happens, it could be for different reasons (none of them good). You’ve already found 1 possibility – “At which time I had to refill the engine coolant tank from mid-level. Which was mid-level again by the oil/filter change. Hmmm.” As others have mentioned – cold climate, lots of short-tripping, rarely getting engine up to full temp – yes you can definitely get condensation, exacerbated if your PCV system also has issues.

It’s a very common problem on Kawasaki Mule UTV’s that are started cold/shut off after a short ride and this pattern is repeated frequently. On later models with their ridiculously long dipsticks, many instances of the dipstick rusting to the point they disintegrate.

My to work trips are at minimum 10 min - and get warmed up due to highway time.
Time to home may indeed have some shorter run times due to errands on city route. But warmup is shorter due to some heat being retained.

And of course we had many fun below 15 F days in a row where I was driving my normal routes.
I skipped the weekend with around 0 F that had the snow.

Since I failed to inspect the cap during the 20k inspection, and it's been warmer since - I likely missed the fact it was already there.

I'll be watching the coolant levels - once I refill engine one again.

 

[HeyBales]

There is definitely moisture in the oil, the question is where it came from. The fact that the coolant has been low twice is very suspicious, a simple pressure test of the cooling system should tell you if that is the cause. It certainly could be condensation, I had a car that had the same issue, actually worse. It happened in the winter and the car was used for short trips. My mechanic told me to change brands of oil and get it out on the freeway once a week and the problem went away. Once the weather warmed the freeway trips were no longer necessary.

I'll have to see if my pump system gets high enough - I don't think so.

There has been the release of air after it's cooled, and slight rise to coolant level.
I'll confirm later, but I don't think the difference is mid-level between the two.

 

[HeyBales]

Both hybrid coolant caps appear to be identical.
Looking at the caps it certainly looks like there is a pressure relief spring inside same as the old ones.
As you unscrew the cap it will allow excess pressure to vent around the sides.
Just a guess.

Just inside the tank cap area - you'll see a little square "hole" where the coolant goes if it escaped the seal.
It lands on the engine mount metal right below the caps.
So it appears easy to see if you've had pressure blow by, as it would stain.
Water shouldn't be getting up that high to confuse things.

 

[HeyBales]

Except a lot of leaks would be helpfully caught by the felt-like under-panel instead of the pavement.

Was inspired to check my 2024 hybrid just now. Coolant is a bit low, only to where I have mild concern and will be leveling off and checking more regularly. Oil cap had just a bit of foam, not nearly so much as @HeyBales. Oil and dipstick look a-ok.

Now I feel good about extending my drives during cold weather. Mostly it's been a vanity thing, that I want to achieve better mpg -otherwise with morning temps in mid-teens °F and a 3-mi commute, fuel economy has taken it in the chops. In the back of my mind burning off condensation was certainly a thought as well.

I try to go long enough for a half-mile full electric once the engine block is up to temp. Probably a good metric I suppose. Also I take it at freeway speeds for a 12-mile round trip weekly. This morning I barely had time for the minimum commute, so perhaps the malted oil cap is just from that.

edit: oil & dipstick observation

I wanted to confirm drips too - so took a picture of hair cardboard!
Yes - I should have gotten another after I cleaned it off.
Yes - I did clean it off. Not washed off of course, just broomed off.
I don't think any signs but the winter splash up.
And finished my inspection with it off too - no signs of drips elsewhere.

 

[HeyBales]

Just changed the oil in my 2010 ford expedition. Same stuff under the cap

So it may be a matter of just not happening at a good time to catch it normally.
Thanks for report.
Or the oil cap is buried in there better.
Prior Rav4 was on the metal valve cover, nice and close to heat.
Even though it had plenty of oil changes close to a cold winter.

 

[HeyBales]

Stop being obtuse.

Mine did it at 10,000 miles.
Mine does it at 56,000 miles.

A little bit at 40°F.
A little more at 30°F.

Never much colder than that but there's dozens of posts that the effect is more pronounced the colder you go and the shorter the drive cycles.

One hot cycle and it's gone.

NORMAL.

This is probably why I didn't see it last year, with some very similar 15 F and below weeks in Jan/Feb.
Probably skipped checking dipstick at fillup too during that time.

But by the Apr oil change - all gone.

Thanks for experience.
Seeing others note it on ICE only vehicles reassuring too.
I've just never usually had short trips - always enough time warmup.

But "short" changes when down to 5 F!

 

[HeyBales]

Retired 40 year auto tech that's common during cold weather driving short trips, if your losing coolant ask them to perform a chemical block test procedure that dectects exhaust gases in cooling system. It's a noninvasive simple test

Good idea.

Because my 6 month checks of coolant strength (per scheduled maintenance) keeps showing it stronger - despite adding distilled water to top off mid to high level.
Because the level has always slowly gone down, very slowly for 6 month compares.

This last inspection with oil change soon after was the fastest drop I've seen.

I haven't researched if the refractometer would be effected by exhaust gases in the coolant.

 

[Chops]

The Hybrid has a “Heat Exchanger” under the truck near the toasty exhaust pipe. Per AI…,

“This component has been a common failure point in Maverick hybrids (coolant leaks from cracked welds or corrosion, triggering codes like P2C22/P237D or low coolant warnings), often covered under warranty or TSBs. It's visible under the vehicle near the exhaust mid-section, with coolant lines running to it.”

 

[Master Blaster]

Take it for a long all-afternoon highway drive in sport mode to keep the engine always running. That should evaporate the condensation in your oil. Then think about using an oil that is specially designed for hybrids at your next oilchange.

 

[Chops]

Take it for a long all-afternoon highway drive in sport mode to keep the engine always running. That should evaporate the condensation in your oil. Then think about using an oil that is specially designed for hybrids at your next oilchange.

There was a previous post ( can’t find it now) that showed someone using Mobil One Hybrid Oil (5,000mi changes) with lots of “mayo” on his cold weather Maverick’s oil cap.

Maybe that is where the special additives put the water - trapped in microscopic bubbles away from the engine up on the oil cap?

The Valvoline Hybrid Specific Oil claims to “trap” the moisture - but doesn’t tell us where it puts it. Oil cap would be a good place?

 

[MYNOMAV]

My 2010 expedition does this every winter here in Wisconsin. It has 210,000 miles. It used to bother me but it just keeps going. I use motorcraft synthetic blend in that and also the 2007 mustang which has 185,000 miles but no winters. I'll have to check the hybrid but I just ran it 170 miles today.

 

[HeyBales]

Take it for a long all-afternoon highway drive in sport mode to keep the engine always running. That should evaporate the condensation in your oil. Then think about using an oil that is specially designed for hybrids at your next oilchange.

Like this which I have used?

 

[HeyBales]

The Hybrid has a “Heat Exchanger” under the truck near the toasty exhaust pipe. Per AI…,

“This component has been a common failure point in Maverick hybrids (coolant leaks from cracked welds or corrosion, triggering codes like P2C22/P237D or low coolant warnings), often covered under warranty or TSBs. It's visible under the vehicle near the exhaust mid-section, with coolant lines running to it.”

That was one of the 20k inspections - but considering it could be so slow, I should check again after a longer drive, and quicker after I stop.

But it was the engine coolant tank specifically that was low - not the EV coolant tank for that exhaust exchanger and DCDC Converter.

 

[Glen Baker LLC]

My 2010 expedition does this every winter here in Wisconsin. It has 210,000 miles. It used to bother me but it just keeps going. I use motorcraft synthetic blend in that and also the 2007 mustang which has 185,000 miles but no winters. I'll have to check the hybrid but I just ran it 170 miles today.

If you can and it's convenient take a look and picture at the oil fill cap in the morning after sat all night and is cold.

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