Hi all,

Thanks in advance for your advice.

I purchased a 2009 ML 63 last year. It is relatively low miles (~50,000). It has been a great driver, and it feels as well maintained as its extensive service records indicate.

2 days ago, I received a low coolant warning. I topped this up with a relatively small amount of fluid, and the car drove fine (around 10 miles total). Yesterday, I again got the warning. Topped off again, but this time it took significantly more coolant. I became suspicious. The car continued to run normally for the next couple miles back home. At a light I noted a very slight roughness to the idle - like one cylinder misfiring. I immediately pulled into the nearest parking lot and turned off the vehicle.

It never overheated. I had it towed to a nearby specialist indy shop. He confirmed that there is coolant in the oil - not surprising. To my surprise he was dubious about the head bolts as the cause. Given totally normal behavior leading up to this, with normal engine temps (and normal rise with driving), it seems likely to me. He recommended to me that he start looking for a rebuilt motor. This didn't make much sense to me without pressure testing cylinders, bore scoping, +/- oil testing for potential bearing wear. I'm unsure if this is possible with contaminated oil, though I imagine it may be.

I'm obviously bummed. I really enjoy this car. I replaced all 4 air shocks just 2 months ago, and it is otherwise in very good shape.

My options seem to be: 1. Take to another mechanic who is willing to do more diagnostics to see what we are dealing with. Then, if all looks good (as good as it can), proceed with a bolt replacement + head gasket replacement, knowing that there is potential for further problems upon cracking into the motor (buckets, phasers, etc.).

Would anyone do anything different? At what point would you sell as is to a DIY-er?

Thanks!