Well Caltex coolant is good it helps in engine heatup as well.
About the radiator service now there are two ways to get it service one is they will open up your whole radiator likee the uper and lower tank than clean the lines which is i dont like.
I always ask them to take out the radiator put some taizab that they use on it than take it to service station and wash it with water. that works as good as the full service (tested) and no risk of leaks 
Another trick my mechanic do is he asked me to put 3 to 4 spoons of Surf Excel in the radiator than run your car for 1 day than take out the water. than repeat this one more day flush the water put pure water in than run the car for a day than flush this water out put coolant and in :p. I tried it and ya a lot of rusted water can be seen on the 1st day btw i wont recomend any one to do it do it on your own risk but i do it and i faced no probs.