The M52/M54 CCV systems do not fail out of nowhere. Mater of fact they do not "fail" and cause the engine to hydrolock.

What happens is on some cars, depending on how they are maintained (or lack of being maintained), how they are driven, in what climate they are driven and if the thermostat has gone soft the Mayo can build up inside the actually CCV valve and some of the hoses and then the Mayo can and will freeze. In most cases the freezing of the Mayo does not damage the CCV or the hoses, but it can cause the valve cover or valve cover gasket to fail in extreme cases. But by the time the CCV freezes it is usually about time to replace it anyway. But in some cases people have had CCV freeze ups on systems that were only months old.

When the Mayo freezes inside the CCV system a few things can happen. The CCV valve will not regulate the engine vacuum and venting correctly and crankcase pressure builds ups and will force oil up the dipstick tube it can be sucked directly into the intake. In some cases the dipstick will pop out due to pressure build up and you will have a mini volcano under the hood and the valve cover gasket can be blown and in some cases the valve cover can actually be cracked.

Some of the V8 engines also have some problems as well, not sure they are as bad as the I6, but I know BMW offers a heated and insulated CCV hose kit for some of the V8's.

The thermostats do not usually "fail" open, they can, but almost every thermostat I have investigated and analyzed had a weak main spring that causes the thermostat to loose its preload and it just opens too early. This can cause the engine temperature to operate too low and this is usually not a problem until the ambient temperatures drop below 70F. With the temperature gauge being buffered in these vehicles the low engine temperature goes unnoticed for some time. The temp gauge stays at the 12 O'clock position over about a 50F range. It is not until deep into the Winter that people may start to notice the temp gauge is not at the 12 O'clock position.

Overall proper engine oil change intervals for how the car is driven can and is essential. Not every vehicle in every climate and ever driving pattern can have the oil change interval at ever 15k miles. BMW should have had a different algorithm other then fuel usage to determine the OCI. They should have taken into account average ambient temp, average engine temp, average MHP and so forth. BUT this would have required Marketings approval and sign off.

The CCV system really comes down to M&M, Maintenance and Management. The problem is people do not open their hood, check their oil, check under the oil fill cap, monitor the engine coolant temperature or pay attention to how long the vehicle has been driven.

Regardless of how large the oil sump is, the oil can become prematurely contaminated if the engine oil never reaches and stays at a solid operating temperature for boil/cook off moisture and fuel in the crankcase. With a 8-9 quart oil fill capacity, it can and will take 2-4 times longer for the engine oil to come up to operating temperature than the engine coolant. If the thermostat is soft, you may never get the oil up to temperature unless you take some very long continuous drives and even then the oil may be just on the edge of reaching the proper temperature to "cook" off contaminates.

We see more problems with frozen CCV systems in the Northern part of the US and in Canada during the Winter. The common denominator with most of the failures is a combination of soft thermostats and short commutes. Many in Canada live close to work and often walk or ride a bicycle or public transportation the 3-6 miles to work, but then the hard Winter sets in many may choose to drive. But this is really a BAD thing for any vehicle, much less a BMW with a 8-9 quart oil sump, a soft thermostat and a CCV system that can freeze.

Anyone that pays attention to what is going on with their vehicle can easily avoided if the oil is changed in the Fall, the thermostat is verified to be good by monitoring the engine operating temperature and to check the underside of the oil fill cap once a week.

Some may not think this is the way people need to operate a vehicle, but there are many engines, BMW and otherwise, that are ruined or severely damaged or just sludged up because of how the vehicle is used and under maintained.

__________________
2008 4.8i Black with Tabacco. Black Y-spoke wheels and shadowline trim.