Coolants and stags - caution if you use green coolant and have the ceramic insert

A word from Vic I have read some of the to and fro on coolants for the Stag. My understanding is that red coolant is used in more modern vehicles with aluminium radiators, and is not suitable for vehicles with copper / brass radiators. However, there are a few Stags around with aluminium radiators...... But this is not what has prompted me to send out this email. Based on my experience I am suggesting some caution in regard to green coolant, especially if you have the ceramic insert in the water pump. I am now on my third ceramic insert, and suspect the green coolant may have been the issue with the first two failures. The first two ceramic inserts lasted a few months before they started to leak. In the first failure the ceramic ring was scored and the rubber in the water seal had failed. I thought this first failure was a one off, and bought another kit. When the water pump started to leak the second time, again after a few months, I took a closer look. The cause of the second failure - scale had built up between the graphite seal and the ceramic insert. Again the ceramic ring was scored, and the ultimate cause of the leak was when a section of the scale build-up on the graphite seal came away; this gave a gap for the coolant to seep through. I now think in the first failure the scale caused increased friction between the ceramic and graphite rings, causing the spring inside the seal to tension and the rubber to fail. I had not heard of this problem of scale build up before, but information from Mr Google suggested green coolant can release silica precipitates if the vehicle is not used often, and also phosphates if hard water is used. The Nulon blurb states that red coolant is more stable than green and will not form solids in the cooling system that might wear water pump seals, however the red coolant is not suitable in cars with a copper / brass radiator. I am now using Penrite Classic Car Coolant corrosion inhibitor, and so far so good. Note I am aware of other Stags with the ceramic insert conversion using green coolant with seemingly no problems, I am just relating my experience. So just suggesting a word of caution! If the seal fails again, I think the next step would be an electric pump conversion! Graeme, you would be happy.