Thx. I'd guess it was the 5W-40 then...that low starting TBN of 8 doesn't lend itself to a long OCI but still, that sludge is scary to look at.

I'm thinking that the main reason for sludge buildup in AMG engines is because they are designed to be high RPM, high output engines, but run below 2,000 RPM most of the time at speeds below 70 MPH. I think that frequent "Italian TuneUps" would alleviate this issue.

Pardon my ignorance but what is an "Italian tuneup"?

take it on the highway and drive it hard!

I think mine gets Italian tuneup couple seconds once in a while

Merging on the freeway at 5AM - WOT.

Also, All my cars get a oil change every 5k miles / 1 yr which ever comes earlier.

Is that a HUGE oil galley?

Weistec Catch Can helps a lot.

In order to increase revenues, most dealers will lie to you and recommend 3,500 change intervals. Both my Mercedes and Porsche dealers recommend going by the book, which is 10,000 and 15,000 miles respectively. Anything under 5,000 miles is overkill. Unless you run the ***** out of it. But it's your money. Have fun.

Shifter is this a head bolt issue. If so the sludge could be caused by coolant leak

True, This car was getting updated head bolts installed

Catch can doesn't do anything to alleviate sludge build up within the engine. They're design/purpose is to keep oil out of the intake tract. The photo shows the head/cam gear.

Ah hah! Still hard to see a performance car go that long without oil changes lol

Do the 2012 5.5 Litre Twin-Turbo have these same issues with bad head-bolts? Hoping that someone else might be kind enough to let me know if this engine has any other frequent or chronic issues

I have 7500 miles on my 2010 and the cars has had 4 oil changes

Coolant contaminating the oil and a 15k mile oil change, that will do it.

They will profit off parts in long term. Where else are you going to get most of your AMG parts other than the dealer. Most people don't service unless there is an issue outside of "Factory service". Only conclusion i could come up with.

No one has asked how this sludged engine is operated. It looks like many short trips to the store before full operating temp is reached and then shut down, especially in cold climate. Many such cycles could do it. Have to agree that our lightly run C63 with annual oil changes @ 5K miles produces normal appearing oil, but always running at full temp. I believe this is at least the second such picture of similar looking sludge, but cannot remember where in the forum.