Milky Oil In Cap

Fellas.... I was doing some under hood inspections today and noticed a little bit of milky oil in the letters and some water bubbles inside my oil cap. Should this be something to worry about? I haven’t seen any coolant loss in the reservoir.

 

My first guess would be a head gasket.

 

the oil has about 1,000 miles on it, when I last did it the oil looked normal. The truck does sit all week and is used for mainly short trips a lot so I have read that can cause some condensation.? I’m hoping....

 

I used to see that from time to time on my Tacoma, never had any problems.

 

That is the most likely explanation.

There is a reason for the crank case ventilation system after all. Pull your dipstick or drain your oil, if it looks okay then you are probably fine. A true HG coolant to oil leak will make all your oil look milky, not just a very small amount on the cap, condensation there is normal.

 

I’ve never dealt with anything like this before so I’m just a little confused, my 1996 Tacoma has 300,000 miles and cap is perfectly clean so that had me a little nervous.

 

It depends a lot on how you drive. Sitting long times and short trips are notorious for this. Normally some moisture gets into the oil from blow by through your rings but when you fully warm up the engine the oil is at about 180º so the water evaporates out and is sucked through your PCV valve and re-burned, but short trips can mean it never runs long enough to pull all the moisture out. When you shut off your engine that water vapor just hangs out in the crank and can condense on the inside of your cap.

Now, of course head gaskets CAN fail but the amount you are showing in your photo looks just fine. Now, if you pull your dipstick and the oil is milky thats a problem.

 

You don't have to drain much to check it. I'd pull the plug and let a cup out and see what it looks like. That's if I couldn't see what color it was just from the dipstick.

 

Mine did the same thing cause I had a one mile drive to work. Never enough time to heat up. In saying that truck has 230,000 miles when I got rid of it.

 

This. Short infrequent trips the condensate can accumulate.

 

I concur, too many short trips. Next time take the long way home LOL

 

You just found your culprit: short trips.

 

Agree my 02 will do that if I do short trips.

 

Not that it is a rule of any kind, but in the past I've associated a sweet smell to my exhaust (anti-freeze) as a sign the head gasket may have failed or a crack in a coolant passage in the head. Just saying...

 

This is accurate. If it's bad enough you can get misfire codes as well.

 

I have also heard tasting the water that comes out of the tail pipe could help if it’s sweet also. It smells good and doesn’t steam. I think I’m going to drain some oil out tomorrow and see what it looks like. I’ll check the dip stick later tonight when I get back home too.

 

Well don't get carried away in the tasting. Pets die all the time from drinking the stuff. Duh.

 

Could my PCV valve being original contribute to any of this by chance too?

 

No.

 

That’s a Texas sized 10-4

 

Hand Model posted a very similar picture to yours a few months ago. I agree with the others, likely nothing to be worried about

 

Damn must have missed it, oil looked good tonight. I’m going up in the hills early tomorrow for a few hour drive to find some elk so I’ll check the cap after putting 100 or so miles on it. But I feel pretty good about it after you guys helped talk me down. Thanks for the help guys appreciate it

 

Small cracks in the head will do this as well. And spit water right into the oil up top...

 

Well, it won't go away unless you clean it off, but it may not occur again if you clean it off and drive for long enough to heat up all your oil and get the trace moisture out before shutting off the engine.

But what you have right now is not a problem regardless of why it's there. It's only a problem if it gets dramatically worse.

 

Plastic caps, especially on plastic extentions are always prone to this when the engine driven short trips.

 

Adding to the mix of diagnoses/solutions here.

Back fill: My truck is a 2002 4.7L. Never had a problem (snot on inside cap) until I made a switch over to full synthetic oil. Truck for 17 years ran on dino and then was moved to syn/blend.

In 2018, I took over maintenance on the truck and decided on Mobil 1 Extended Performance Oil Full Synthetic as it was on sale and came with the Mobil filter. A thousand miles on the oil I noticed a finger tip of snot on the cap. Also, I noticed (very slight) weeping around the oil pan gasket. This oil has high parafins in it and the molecules are very uniform so older gaskets can’t handle the new tech.

I did also observe a slight oil film on my last coolant drain and fill right after the initial snot observation.

Theory Conclusion: Some coolant leaked into the engine case due to the high detergent action and penetration of the syn oil. This is fairly normal on most cars regardless of oil type from my readings.

I cleaned the snot off and monitored the cap. Changed the oil another thousand miles in over to ‘High Mileage’ Mobil 1 Synthetic which has seal conditioner. Weeping has stopped. I’m on my 3rd oil change since last year. Engine feels peppier now than last year.

No film currently on the coolant. No snot on cap. Lessons learned and should have put High Mile Syn in the first place, instead of the Ext. Performance.

Here is a good link from a shop owner about the subject. You can link around and learn more.

http://www.agcoauto.com/content/news/p2_articleid/122

Report back on your new oil type Phil.

 

I’d highly recommend installing a new PCV. Don’t believe me, but read what a shop owner says. Its such an inexpensive and easy job.

http://www.agcoauto.com/content/news/p2_articleid/197

 

Good to see you back dude!!! Everyone’s been asking about you!

 

Take a nice long drive and check the cap and the dipstick. That's probably condensation from the short trips. Getting the engine up to full temp for a while will evaporate the moisture. If it's a problem, the oil on the dipstick will still be milky when the engine's at full temp.

 

Thank you. Been busy with Dereks Center for Kids Who Can’t Read Good. Glad to be missed.