Oil sludge-ing in ~300 miles, tripping pressure sensor?
 

My wife's baby (aka her 07 R56) is having a problem, and I'll be a hero if you guys can help me fix it...

07 R56 with only 50k miles. I've been doing regular (5k miles) oil changes for the life of the car. Lately, the red oil pressure light has been blinking on/off while driving. The first time this happened, I checked the oil, and found a lot of oil/water emulsification sludge under the filler cap, but it was almost time to change the oil, anyways, so I changed it, and the problem went away.

Then, ~300 miles and ~6 weeks later, it started blinking, again. Again, lots of sludge under the filler cap. I wanted to measure the oil pressure, but couldn't find an M16 fitting to attach my pressure gauge....thought I'd just change the pressure sensor, but got sent the wrong part. So I gave up and, out of desperation, changed the oil (and filter), again.

The oil was like chocolate milk. And when I changed it, the problem went away (again).

Using synthetic oil, OEM filter, no white smoke from the exhaust, and am NOT losing any coolant.

So why is the oil getting so sludgy in ~300 miles, and why is this causing the pressure light to flash? I'll admit that my wife makes only short trips (~6 mile commute, 2x/day, 6 days/week) and it's been very cold, here (~0F), but would this be normal? Does she just need to take a longer drive with it every few weeks while it's this cold?

If you're positive the coolant isn't finding its way into the oil then I would say to start driving the car more, or harder so as to "boil" the condensation out of the crank case created by short trips.

Thanks nkfry. Other than watching the coolant level in the overflow reservoir, is there anything else I need to do to confirm it isn't a head gasket problem?

Short of pressure testing the cooling system, doing a leak down test on the engine, or sending oil out for a Blackstone analysis there isn't much else you can do.

It takes a significant amount of coolant to turn 5 quarts of oil into a chocolate milkshake, so if that was the case I would almost guarantee that you'd notice the coolant levels dropping.