2012 M3 white mucus in coolant reservoir

[fischerkd]

I've got a 2012 M3 E93 with 48k miles on it, bought used 3 months ago. I changed the oil right away with 10w60 castrol supercar and burned about 1 L of oil in the first 1000 miles of the oil change (within BMW's oil burn rate standards for the M3).

The car runs well and at the 1000 mile mark of the oil change I went on a 2000 mile road trip, including a large section of California's highway 1, driving the car hard most of the way. Before leaving on the trip I added about 10 ounces of distilled water to the coolant reservoir to bring it up to level - and I noted then that there was a small amount of white / yellow stringy mucous-like substance at the top of the reservoir. I attributed it to someone in the car's past putting in off-brand coolant.

Now returned from the trip, the coolant level hasn't budged. The same amount / quality of mucus sludge is in the reservoir (floating atop normal looking coolant). The burn rate of oil is ~0.5 L for the 2000 mile trip.

Thoughts on the source of the mucus sludge? My reading tells me it ranges from bad or wrong coolant to a blown head gasket.

Thanks all - 1st post.

Kevin

[fischerkd]

UPDATE to this issue. I ended up flushing the coolant system multiple times around a water pump and thermostat replacement, taking the opportunity to replace most of the coolant hoses. In my case, the mucus was primarily collecting in the reservoir and I eventually eliminated it from my system through the use of paper towels, swabbing out the interior and removing them with a long tweezer. The mucus has not re-collected and I'm not losing coolant, leading me to presume that a tech at CARMAX topped off the coolant reservoir with non-conforming antifreeze before I bought it, leading to the creation of the gunk. Annoying, but the preferred outcome.

[IS300]

i think you are right!!!!!

[heco94]

This looked very reminiscent of the sludge first gen VW direct injection engines would get on the oil filler cap, granted that isnt the same thing. That was a normal part of those engines.