Gunk in the oil filler cap (1 Viewer)

[Buddysuede]

Has anyone seen this funk form inside their oil filler cap before? If so, what's causing it? I use Mobile 1 0W-20 synthetic and I've put 5500 miles on the truck since my last oil change. Any ideas?

 

[bjowett]

Condensation... too many short trips w/o warming the engine oil thoroughly. Usually nothing to worry about.

 

[gaijin]

The only time I've seen gunk like this on the inside of the oil filler cap was when I had coolant mixed with the oil. That was on my '67 Saab 96 V4 and the cause was a cracked block allowing coolant to migrate to the oil. Could also be a blown head gasket.

There are test kits available to test motor oil for coolant contamination - it might be worthwhile to test your oil.

HTH

Edit to add:

How Glycol is Detected in the Field
Astute mechanics, lubrication technicians and operators are always on the lookout for the telltale signs of a lubricant contaminated with coolant. In truck, bus and mobile equipment fleets, the first sign might be white smoke billowing from diesel engine exhaust pipes. Or it might appear as a shiny adherent sludge having the consistency of mayonnaise on a used filter during a routine change out. Perhaps as previously mentioned, the oil pressure in a diesel engine runs unusually high only minutes after an oil and filter change.

Interesting article can be found here: Glycol In Lubricating Oil - Detection, Analysis and Removal

 

[studawg]

I just changed my oil and had that sludge in the cap. Had about 7500 miles on M1 5w-20. I have sent the oil to Blackstone for analysis because I want to extend my oil change interval as long as possible. I will report back if there is anything like coolant in the oil, but I think its just condensation.

 

[Buddysuede]

Thanks for the feedback guys. I ordered a Blackstone kit to send out a sample on the next oil change. I'll repost with my results as well. A quick Google search provided numerous links talking about the condensation and or head-gasket leak.

What is this white milky stuff under my oil cap?

Hopefully Blackstone will put our minds at ease.

 

[CLHickman]

The photo was of my oil change. I am going to do another oil change at half the interval, so another 2000 miles. I did review the dipstick and also reviewed the cap after a 100 miles and I've got no gunk.

 

[Buddysuede]

A friend of mine who runs an oil change shop says 90% of the cars he sees in our area come in with this. He said to make sure the PCV valve is functioning properly though.

 

[studawg]

Ive seen a few instances of this in some of the newer Toyotas, there wasnt anything wrong with any of them.