[Kentetsu]

If this is not a turbo motor, then you might consider adding Alumaseal to the radiator. If it is a turbo, then I would be worried about the potential of causing issues with the turbo.

My 12a had huge coolant issues blowing white smoke out the exhaust. Added a bottle of the Alumaseal to the radiator and it was gone within 30 minutes. That was over 20,000 miles ago. Might be something to consider, but use it at your own risk. But be specific when you pick this stuff up, because other brands (like block sealants) turn into a cement type substance that really plugs shit up and can trash your motor. The Alumaseal remains softer like a silicone, and does not seem to cause these problems.

Good luck...