3.0 tdi head gasket failure?

[luminova11]

Hi,

Just had a low coolant warning,  so topped up. Checked the oil filler cap and find the telltale sludge showing water in the oil. Probable head gasket failure. Before I bite the bullet and put it in for the heads to be done, is there anything else that could be causing the problem? 2013 Q7 3.0 V6 Tdi.

Also anyone have a ballpark figure for head gasket replacement? 

Thank you.

[ber5ien]

Already to late to respond but for feature reference this is most likely oil cooler seal.