Hi Ken.
I used to have a problem with my plus 8 overheating and boiling up, when I got stuck in traffic. Therefore losing usually quite a lot of coolant. This was a worry especially if swmbo was with me, as she would usually give me an ear bashing.
I did a bit of research at the beginning of last year and spoke to various people about the problem. It was recommended that I fit a Mulfab Ally Radiator and a 14" fan, which I did. As the radiator was quite an expensive item I also decided to use Evans Waterless Coolant to protect it and the cooling system from further corrosion, coupled with the high boiling point of Evans coolant.
The result has been really good as the engine now runs at a steady 90 / 95 deg C even when I am stuck in heavy traffic.
Last year I drove down to Lemans 24hr race and got stuck in heavy traffic in 30 deg of sunshine. The Mog held the normal running temp at all times, I have never had to top up the coolant since.
I now have more confidence to go any where.

I hope this helps?

Steve
1997 Indigo Blue +8