So lately it's been one issue after another with this car. Today I get a new dash msg saying oil sensor defective. So I go to check the oil and I'm low so I remove the fill cap to find THIS. I'm screwed ain't I? I'm guessing I'll be doing a head gasket or two in my near future won't I? How much of a PITA is this to do? Is there anything I should know about prior to diving in? Any help would be most appreciated!

 

Ohhhhhhhh yes defo looks like the classic head gasket symptoms.
Kinda reminds me of my old rover k series back in the day, head gasket every six months or so bloody things.
I cant say i have done a head gasket on the merc but i dont see anything that would make it to hard of a job, or should i say harder than normal.
Im sure somebody will have done this job on here and give you some advice.
Almost forgot to ask, have you noticed any water loss from the header tank....

 

Ok so the update is good ( I think/hope?) I spoke to the mechanic at my usual shop. He says that's totally normal with these cars due to condensation and cold temps outside. He had me check a few things and all looked good. The coolant has not gotten any lower, the oil on the dip stick is clean and clean with no mayonase, it's not blowing any white smoke and the engine temp is normal. So I'm praying he's right!! What's your thoughts? Is he??

 

Just keep a eye on the header tank level over the next few days, although i have got to say that is a lot of creamy gunk for condensation.
Keep your fingers crossed mate.

 

He's roght, but my experience was to replace the thermostat at around 100k. Change the oil and avoid short trips too.

 

I'll tell ya I almost died when I saw that as I had just walked out the door to head to work. Come to find out the defective oil sensor was just a result of the oil being a little low. I topped it off and that warning immediately went away. Luckily I drive an hour one way to work so once I get the oil changed (within the next week or so) we'll see how she does and what comes out of it. So far it all looks good aside from what's on the cap anyway. I'll keep ya's posted

 

Good news man! I'm glad it wasn't another big problem like everything else you've had to deal with

 

+1 with condensation. In my experiance with blown head gaskets usually the oil level is above the full mark from the coolant mixing with the oil or tons of white smoke from the exhaust. When I got my 420 the oil cap was like that. I change my oil once a year cause I don't put enough miles to change sooner and I make sure to take my car on a longer ride then just to work and back at least every other week. I haven't noticed any milk on the oil cap in the since I got the car in 08

 

http://www.offroaders.com/tech/milky...er-oil-cap.htm

 

Yep, I was shocked the first time I saw it a few years ago. My engine is fine

 

I bought my E430 in 2/12 with the same issue,it's completely normal for these cars.Condensation build up etc. combined with short vehicle trips causes this.

 

Similar posts on the BMW X5 forum I follow. Cold weather + short trips = "yellow pudding". Most advise to take the car out for a nice long (30+ minute) drive periodically to get it up to temp and usually that solves it.