I have a 2013 991 Carerra S Cab with 39k miles on it. I unscrew the oil cap to add some oil and there was a strange yellowish gunk on the top of the oil cap that smelt strange, I guess a bit like alcohol. The car is running perfectly. Is this normal and just due to old oil? It was changed around 30k.

 

I've only heard of this a handful of times in cars that only take short trips and never really run at operating temperatures for long periods of time. This really pops up during change of seasons where moisture is at it's highest and doesn't get burned off before shutting down the engine.

I would clean the cap and do more frequent oil changes at 5K or so and it wouldn't hurt to send off a sample after the next oil change to see if there is any coolant in the oil.

 

Ok, thx.

The car does 15-20 miles a day during the week, then 300 at the weekends.

 

Last time I saw "yellow gunk" on the inside of the oil cap, the engine blew a head gasket. Have you checked your coolant level?

 

No I haven't checked the coolant level, how do you do that?

The car doesn't overheat though it seems to be running normally.

 

For coolant level, wait for the car to be at room temp, easily open the expansion tank cap, and check the level in the tank.

 

Get a sample of the oil and send it to Blackstone Labs. That'll confirm the possibility of oil contamination.

 

FWIW in cold mid-west winter weather even with a similar usage (well, maybe not 300 miles on weekends but sometimes 150 (round trip) to my parents) I'd see a touch of this gunk.

9K miles on oil is kind of a lot in my opinion. What I found early on -- via an oil analysis -- is water builds up in the oil something fierce. At just 4K miles from new my Boxster had approx. 7% water in the oil. That's nearly 1/2 quart of water. What I found is even at freeway speeds in cold weather the coolant temp doesn't get very hot and the oil stays cooler too.

The crankcase is often under low pressure which lowers the boiling point of the water but this is not able to remove 100% of the water, so water accumulates in the oil.

The water vapor that gets up around the oil filler tube and cap area is in the coldest region of a running engine and the water vapor condenses and catches some oil vapor droplets with it and the gunk is the result.

You can send a sample of oil out for analysis. It is important you gather a sample the right way. Among other things the analysis will tell you the amount of water in the oil and if there are any anti-freeze compounds. If the later this is a sign of an intermix problem and with these engines the word is more often than not it is a cracked head but an oil/water heat exchanger leak can be the cause, too.

If you do the analysis I believe you'll find there is probably some water in the oil but I doubt any anti-freeze compounds.

Change the oil more often. Based on the results of the early oil analysis I elected to change my Boxster's oil every 5K miles and have since then and the original engine has over 308K miles on it and still runs as good as it ever did.

 

Macster,
That is a very interesting reply, thank you. I will try and get it to the dealer this week end and see what they say.

You really have 308,000 miles on your Boxster, that is amazing?!

No issues?

How old is it?

 

7% water? I would have towed it straight to the dealership! Here's a small section of my last report. Column 2 is at 23K miles, 4 is at 18K.

 

This has nothing to do with contamination. It is the evaporation of water and corresponding contaminants. I routinely flew aircraft where this was the norm. The solution was to remove the cap until the engine cooled. The gunk disappeared.

 

Interesting discussion. Back in 1976 I had a 356 S90 and that happened in Monterey, CA after I changed the oil using Pennzoil. I blamed Pennzoil and changed it. It never happened again. That is obviously not very scientific, just an observation but clearly, coolant was not getting into the oil.

ChuckJ