Both Cinqs and Seis suffer with head gasket failures. There's no predicting when they will go, some will last for ever and some wont.

Tell-tale signs vary, if yours has gone you may have one or more of the following symptoms.

• Creamy deposit in the cam cover and under the oil filler cap, caused by water getting into the oil.
  
• Oil in the water.
  
• Oil or water leaks from the engine block.
  
• Gradual loss of coolant with no visible cause. (e.g. max to min in a week or so, if it occurs over several months this would not neccesarily indicate a problem)
  
• Misfiring when cold for the first few seconds after starting up, caused by water getting into one or more of the cylinders.
  
• Persistent misfires, especially when using heavy throttle at low revs caused by leakage from the cylinder past the head gasket.
  
• Overheating

The most common cause of gasket failure is corrosion inside the water passages, this creeps past the gasket and causes it to fail. Regular (i.e. annual) change of antifreeze will minimise the probability of this. Check for this in the service history when buying used.

torques & tightening

• stage 1 22 lbf ft
• stage 2 angle tighten further 90 degrease
• stage 3 angle tighten further 90 degrease

• tighterning order
• 8,6,2,5,10
• 7,3,1,4,9

thanks to pete(fixitagaintommorow) for the info