Orange/yellow Sludge in Oil Fill Stem and Cap

Went to check my oil today and noticed quite a bit of orange/yellow sludge buildup in top of oil fill stem and in oil fill cap. Never had it before. Just did a 1000 mile trip about a month ago pulling a small 5X8 uhaul trailer that wasn’t loaded particularly heavily and took drive pretty slow with lots of stops and didn’t go over 65mph.

Also noticed my oil level at the dipstick was down at least a half a quart so I cleaned out fill stem and cap and topped it off. Oil color at the dip stick looked normal. About due for an oil change. I run Mobil 1 full synthetic with a puralator boss filter. Not too worried about oil being down a bit truck is 12 years old and seems to be burning a little oil. Just wondering if anyone has experienced the sludge that color at fill stem and what the likely cause could be. My buddy said maybe bad head gasket, but I’m hoping it’s not that.

I will note that since the 1000 mile tow drive truck hasn’t been driven highway at all in last 2.5 months mostly around town rarely on small 60 mph highway. I did read somewhere lot of city driving can cause this. Coolant is pink so fearing head gasket which is causing this Big Mac sauce colored sludge.

Any tips on what it may be would be appreciated.

Also, any tips to test or clean out the system? Thought about doing an oil flush. Never done it before but my buddy said there are some kits on Amazon and I’m sure plenty of YouTube vids.

I also usually put a little seafoam in crankcase before an oil change and wondering if that might be a good test to clear it up followed by an oil change. But don’t want to do an oil change with Mobil 1 if it’s likely it’s something more serious that needs to be addressed before changing oil.

Thanks!

 

Just moisture in the crankcase.

Longer hotter drives will help reduce the sludge. I suggest a 4th gear rip on the highway if it doesn't see much action.

Quality synthetic is a good idea to combat it as well.

It's not a major deal with the 4.0, but it can eventually plug up the screen and vvti controllers.

 

Headmaster or your engine never comes up to temperature for very long

 

Thats head gasket

 

What makes you say head gasket for sure as opposed to moisture from not coming up to temp? Just curious. Never dealt with a headgasket issue before so just trying to understand. Is bad headgasket is most likely is it something I shouldn’t drive until fixed and how costly is it to fix?

 

This mild sludge on a customers truck. Same colour.

HG's mean coolant is entering the sump, not very common on Toyotas, and the coolant would be low, oil would be higher.

 

Mine looks like that from time to time, seems to follow which oil I run. Over 200k, so I keep an eye on it. Some run a catch can to keep it out of the system.

And the dip stick always looks as it should.... so it a vapor thing, maybe valve seals leaving the chat....??

 

Thanks that is helpful. Oil level was a bit low and coolant appears to be same level it was when I topped it off few months ago. I am going to check coolant level in reservoir when hot. May be down a bit, but again like you said oil level would go up if coolant was getting into crank case.

 

My uncle owns a trucking company and knows a good bit about trucks. He said to consider adding 1 quart of Lucas synthetic oil additive when I change the oil. He said it can help with oil consumption. I may give that a try also. But sounds like I just need to get more highway use in. Literally past 2.5 months all I’ve been doing is making close trips around town to the store etc and my job is only 5 miles away now. Did more highway driving previously and never had this issue.

 

Drive it like you stole it

 

Sounds like it needs some lead foot driving! Trucks are similar to outboards I guess they like to be run hard.

 

install a PCV catch can, you'll be amazing by the amount of junk that collects in it. esp all the moisture during the fall/winter months.

 

Thanks I’ll look into that. Where did you get it from?

Was also thinking about changing out PCV valve since I don’t think it’s ever been done.

 

I saw that same amount on a customer's 4.0 two weeks ago. He never drives it

Keep an eye on the coolant level, if it's not going down slowly the head gasket is fine

 

Head gasket failures can manifest themselves in different ways. Keep in mind that a head gasket seals pressurized oil fed to the overhead components (valve train, cam), oil draining back to sump, pressurized coolant going through the head and lastly, seals the combustion gases in the cylinders. So you can have external leaks of any of these fluids (oil, coolant, combustion (not as common)) or intermixing on the fluids depending on where the failure occurs within the gasket. Compression gases getting into the coolant is common which causes bubbling and sometimes overflowing of coolant. Oil can get into the coolant or coolant can get into the oil. Keeping in mind that oil pressure is generally higher than coolant pressure you would think how can coolant get into the oil? Usually, once the engine shuts off, oil pressure goes to 0 but coolant pressure remains due hot coolant being under pressure or it can leak into the low pressure oil drain back. It all depends on how the passages are all arranged in the gasket, the type of cylinder walls (free standing or solid), material of block and head, gasket materials, etc. Every engine is different and understanding the history of that engine model helps with troubleshooting to determine most likely failure scenarios.

When I see that amount of moisture in the oil cap I tend to think head gasket but further testing should be done to rule it out. Or it could be, as others have stated, a build up of moisture from condensation inside the oil sump that isn't being properly burned off. Your oil needs to run at a higher temperature than 212°F for the water to boil off (most engine oil runs about 240°F). So either your engine is running cold (thermostat stuck open) or an oil cooler is doing too good a job. Or a lot of water is getting into the sump somehow.

 

I'll echo what everyone else is saying:

• The "goo" is moisture - two main causes are only doing short trips (i.e. not getting up to temperature) or possibly a head gasket.
  
• Your driving habits of short 5 mile trips to work sound like a good fit for the root cause. Drive it more.
  
• If you have a 2011 and never changed the PCV valve that only costs like $5, ABSOLUTELY do that. Do it now. Go back in time and do it yesterday. Always do all the basic maintenance first.
  
• If you want to help rule out a head gasket, they make cheap test kits. Harbor Freight even sells one, it's like $25. Pretty cheap for peace of mind.

I'll also add the following: While unrelated, adding Seafoam, adding Lucas additives, adding this that or the other witchcraft voodoo sauce when you don't have a problem already is silly. Ye old Toyota 4.0L doesn't usually need any of that stuff unless you abuse it! If you do regular maintenance at normal intervals, I bet you could eat your dinner off the inside of the block. Losing 1/2 quart of oil over an OCI is nothing, especially for a 12 year old truck. Hey by all means do what makes you sleep well at night, but just saying don't buy into all the hype of mystery magic snake oil stuff either.

 

160K on mine all ways found a bit of gook on the fill cap. It's the highest point, years ago that stuff was just vented out. I agree with others you need to drive it short little hops just makes it worse.

 

Me too, I would be highly suspicious of a head gasket leakage of radiator fluid into the crankcase. That is way too much buildup to just be never warming up. Something is putting radiator fluid into the oil.

 

How long has your "average" trip been (time/distance)? That does seem like a lot to simply be condensation, maybe unless you live where it's cold/damp and a lot of moisture can develop in the engine/crankcase. Where do you live?

 

I've heard BG makes a great engine flush, though I don't have personal experience with it. The only thing I've ever done, and this was probably close to 10 years ago now, was pour some seafoam into my engine, drive for about 500 miles then drain the oil and refill with fresh stuff. I didn't need to do that, but it made the younger me feel like I was doing something good. Never noticed anything different before/after though.