White Residue on Oil Cap - Castrol 5w40

[akuska]

[Note, I've also posted this to the General Forum, but since it tangentially involves European Oils, and there's a different reader base here, I figured, "what's the harm?".]

I just checked the oil level on my car and opened the oil cap to look inside when I noticed a little white residue on the oil cap and on the rim where the cap screws in. It looks almost like cafe au lait. It's too dark, so I can't see into the crankcase when I remove the cap. However, the oil on the dipstick is still very dark.

Should I be concerned about this? I've looked on some other sites, and get answers ranging from "it's just a little condensation, don't worry about it, all cars do this in the cold" to "there may be coolant or fuel dilution and you may be damaging the head gasket" and everything in between.

Here's some background:
I'm running Castrol Syntec 5w40 on a 2006 VW Jetta with the 2.0T engine. It's been 7K since the last oil change. The schedule is 10K. The car has about 26,000 miles on it now.

We just had a stretch of 10 consecutive days where the temperature never got above 20, and for most of that time we were in the single digits or below zero. Today's the first day near 30 (it feels downright warm!), so it's the first opportunity I've had to take the time to check the oil. As I noted on another thread, I am in the minority who doesn't warm up a car for very long before driving off (slowly, under 2000rpms for the first few minutes). The car gets mostly highway miles at night (city and mild rush hour traffic in the morning) and I have a 20-30 mile commute each way most days.

I usually check the oil level every 1000 miles or so, but because of the cold and a few out-of-town trips, it's probably been about 1200-1500 miles since I last did a proper check.

The car has boiled off almost no oil over the past 7K miles. Previously, the dealer used Mobil1 0w40, which I topped up with GC or M1. It used to boil off about a quart every 5K or so with that blend.

 

[Buffman]

How long are you driving the car for? Long periods or short periods everyday. It's a pretty common thing (unless you have coolant in the oil and that's a whole nother problem). moisture gets trapped into the oil. It will burn off when oil temps get near where water boils (212F or so). If you take a lot of short trips, that moisture will condense in the coolest part of the engine, typically the oil filler cap

 

[akuska]

It depends. It's mostly 20 miles each way, but I also have some short commutes, as well as some 90 mile drives. The last two weeks have been particularly cold (single digits, below zero). I checked the coolant reservoir about 20 minutes after I turned the car off and it was about 40% between the Min and Max lines (I don't remember where it usually falls. The oil on the dipstick is dark as normal. If I think of it, I'll check the coolant tomorrow morning, and the oil cap after I arrive at the office.

 

[Big Dave]

The white deposits are from water/moisture. Basically the car is not getting hot enough for a long enough period to displace all the water/condensate in the engine.

Its directly related to the cold you are having. I saw it a lot when I used to live in Chicago. Even though you might be driving upwards of 20 miles...perhaps it is more stop and go? For sure your 90 mile drive should clear out any moisture.

Another thought, maybe the oil cap area runs cool on these engines. Then even with prolonged driving in very cold temps may not be enough to clear out all deposits.

By the way, I have an '06 GTI with the same engine. Currently run M1 0W-40. I have zero oil consumption. I change oil at 5K intervals. You may not be aware but these engines are fairly hard on the oil. There is quite a bit of fuel dilution and metals seem to be higher than average with a UOA. Might want to do 5K OCI.

I plan on trying another oil next time...Synpower 5W-50?

David

 

[ctrcbob]

Ditto to what David said. Oil not getting hot enough. Back in the "old days" it would happen to me when I lived up there in Snow (and cold) Country.

I remember changing out the thermostat to a higher temp thermostat to get the engine hotter which in turn would get the oil hotter. These new modern engines already have a "high temp thermostat", so you either must change your oil more often, or drive the car more and further, or perhaps just use the old "cardboard in front of the radiator" trick.

 

[akuska]

The coolant level seems normal on my car. I found just a smidge of white under the cap today, again with none on the dipstick, so between all the explanations here and on the similar thread I set up in the general forums, I'm starting to agree with the "condensation" argument.

As for the OCI, I've thought about a more frequent interval, but as long as the car was consuming M1 at 1 quart per 5K, I figured I was adding more additives anyway. Since the Castrol isn't consuming oil, I suppose additive breakdown becomes more of a concern. It's a bit difficult to reach the plug to do a UOA (unless I can figure out how to siphon it from the top), so I haven't done one. The dealer recommends 5K, but I always figured that dealers want to sell more maintenance. Since 15,000 km is the standard in Europe, I figured 9,500 miles should be OK, but European fuel is cleaner. OTOH, I probably won't keep the car too much past 100K. I'll probably tire of it before it breaks down, and I got 100K out of a 1.8T running conventional on 5K OCIs back in the days before I knew about the sludge issues, so I'm less worried about running synthetic in the slightly cooler-running 2.0T. I'll see. Maybe a shorter OCI makes sense in a harsh winter such as the one we've had.

 

[Patman]

I'm borrowing my mom's 2001 VW Golf (2.0 engine) for a few days because of a big snowstorm we're going to get, and this morning I topped up her car with a half quart of GC 0w30. I noticed a lot of residue on the inside of the oil cap, as well as in the area just below the cap. It was a rather thick yellowish kind of goop actually. She does a ton of short trips, in fact she's only driven 2200 miles since last June (that was the last time I changed her oil)

Even with these short trips though, her last oil analysis result came back looking good, so I'm really not too worried about this residue unless I did notice it was causing higher engine wear. Her last UOA was for a 2 year OCI as well, with less than 8000 miles on GC 0w30.

It probably helps a lot when I do borrow her car though, since my round trip to work is 50 miles, and it usually takes me an hour each way as well due to the traffic, so the oil gets good and hot for a long time whenever I borrow the car.

 

[JustinH]

I get this in the dead of winter in my 98 f150.

Probably relates to the short trips I take the truck on.

Nothing to worry about.

 

[unDummy]

Normal in many cars. Some of can be prevented with a PCV catch can or equivalent.
Excessive moisture buildup can lead to sludge.

Just because the OEM recommends a 10k oil service interval doesn't mean you have to wait that long. Depending on driving style, a more frequent OCI can be considered. Take a sample for a UOA to determine a safe OCI inteval for your driving patterns.

 

[casper]

Common in many vehicles...VERY common in VW engines.

 

[casper]

infact...here is a thread on Vwvortex about the issue on the 2.0engine

 

[kapps]

There have been some MINI owners who've had this issue as well. They all have a short commute so the oil is never allowed to get to temp.

 

[akuska]

Would you re-post the link? It didn't show up. I haven't been on the Vortex for a while.

 

[Turbodriven]

I wouldn't worry too much about it, as many mentioned here its fairly common on VW's.
What I would however do is give the car a bit of a hard drive somewhere along your route home, or drive it a longer route home... being a turbo FSI motor it will heat that oil up fairly quickly.