What IS this gunk inside oil cap???

[md13ffhguy]

First oil change for my wife's 2014 FFH tonight. Dropped the panel underneath and was pleased to see no signs of fluid leaking, unlike my experience with my 2013. Then, I removed the filler cap and...WT$*(&^!%(*^????

 

I've had a lot of cars - several new - and I've never encountered this before. Can anyone tell me what this might be? There's also some just inside the engine. I'm assuming I should clean this gunk out... at least that's what I'm going to do.

[GrySql]

Just a guess but it looks like coolant is mixed with your oil. Button it up and see the Dealer pronto, if not sooner. :(

[Texasota]

I googled "yellow gunk on oil cap" and got lots of hits. Most of the discussion was in various forums and it seems to be a common discussion topic. Many of the answers seemed to indicate it occurs when the driving involves frequent short trips where the ICE does not get up to full/normal operating temperature. Assuming that is true, it would seem like the ICE in a hybrid would be very susceptible to this accumulation of gunk. The discussions mostly seemed to indicate that it was not something that is cause for concern and the ICE is not being damaged.

 

If the oil on you dipstick looks normal (not milky colored or gunky), then it is probably not a reason for alarm but having your dealer look at it (as GrySql suggests) is probably a good idea especially if it eases your concerns.

Edited February 7, 2015 by Texasota

[md13ffhguy]

Yep, did that after posting, and was kind of surprised, but also relieved. Her normal commute is short, so maybe that's it.

[Texasota]

Yep, did that after posting, and was kind of surprised, but also relieved. Her normal commute is short, so maybe that's it.

Did the oil you drained look normal?

[GrySql]

The color is what made me nervous.

In my experiences with short trip condensation the 'gunk' was not that color, it was milky white (oil/water froth) and can burn off with an extended driving event.

Take a look at your coolant color and you'll see what I mean.

Edited February 7, 2015 by GrySql

[md13ffhguy]

It looked yellower in the photo than in reality. I don't think there's an issue with coolant leaking into the engine. The drained oil appeared completely normal.

[GrySql]

You might have scraped some gunk into a glass container and sealed it for observation and checked for separation.

You can get oil analyzed, it would be interesting to see what the chemical composition consisted of.

 

Well, now you have something to keep an eye on, I sure as heck would.

[md13ffhguy]

I could have saved some, but I didn't. I'm not as alarmed now as I was initially. Since I'd never opened the cap, I don't know when it began accumulating. Her normal commute is about 6-7 miles each way, and with the cold weather, the ICE probably never reaches normal operating temperatures - at least not for long. I will keep an eye on it, but this explanation seems reasonable, and by most accounts, it's not a harmful condition. She does often make some longer trips, but hasn't done so recently. Maybe we should have bought her an Energi...

[Easy Rider]

Yes it's condensation. Mostly water mixed with a tiny bit of condensed oil fumes.

It is more common in the winter time and with short trips.

By all means clean it off as good as you can but don't worry about it unless you see oil rising to the top of the coolant.

 

It might bear having a look at the PCV system at it's next dealer service. PCV is supposed to eliminate most of that.

[acdii]

That is quite normal to see on cold run engines. It takes 10 miles of driving to completely heat up the ICE, and at least an additional 5-10 to burn off any condensation in the crank case. If you drive less than 10 miles every day, and never get the car up to full operating temp and leave it there for a bit, this is what collects on the cap.

 

The fix, take it for a long drive every once in a while and that muck will go away. I wouldn't waste time going to the dealer for this as they will ask how much is it driven and tell you drive it more.

[Easy Rider]

Just one more small note:

Once you have a substantial amount of the "gunk" accumulated under the filler cap, it might take a LONG time to "burn" it off......like maybe never.

 

Since pretty much nobody else here is reporting that with the FFH's, I still think the PCV loop should be checked.

[acdii]

Then again how many who drive short hops change their own oil and would even have the cap off to look?

[billford]

Her normal commute is about 6-7 miles each way, and with the cold weather, the ICE probably never reaches normal operating temperatures - at least not for long.

If the coolant level is lower, it could be coolant mixing. If not, its probably condensation. The color could be caused by dye. The factory adds dye in the oil for leak detection.

 

I agree that the engine may not reach operating temperatures on short trips during winter and I think the oil change interval is far too long. I change mine every 6 months or 5,000 miles.

[Texasota]

I agree that the engine may not reach operating temperatures on short trips during winter and I think the oil change interval is far too long. I change mine every 6 months or 5,000 miles.

+1

 

My first oil change was free (compliments of my dealer). But for the future oil changes I plan to do the same (6 months or 5,000 miles) and use 5W-20 semi-synthetic. The cost is less than half of the synthetic 0W-20 and my gut tells me that is better than going 10,000 miles even with synthetic. This approach also matches up tire rotations at the proper interval resulting in only one visit to the dealer.

Edited February 8, 2015 by Texasota

[acdii]

Subtract your EV from overall for true ICE miles though. With 40K miles on my car, the ICE has only 23K on it.

[Texasota]

Subtract your EV from overall for true ICE miles though. With 40K miles on my car, the ICE has only 23K on it.

No argument there. But, with Billford's suggested oil change interval and by using 5W-20 I see the following advantages:

• The cost is still less with twice the number of oil chages.
• Fresh oil in the ICE twice as often provides some benefit. How much? Who knows, but likely more benefit in cold or hot climates. Minnesota is cold in winter.
• Tires are rotated at the proper interval. 10k miles for tire rotations results in shorter tire life.
• Results overall in the same number (maybe less) visits to the service department.

[hybridbear]

If you see similar build up at the next oil change after having cleaned it out now then I'd recommend having an oil analysis done by someone like Blackstone Labs.

 

Here's a thread where a C-Max owner has used them.