The hardest thing with the old engine blocks is that you dont know the history of the block. There could be all sorts of scale waiting to come away regardless of the coolant you use. In a new car, using the good stuff from the word go will always give you the best results. (that 5 year stuff with the cruiser is entirely believable).

Unless you have had the block properly acid bathed and cleaned and scaled away, then there is no real way to assume that cause you are using a better coolant, you will get no problems.

Still thats no reason to not use the better stuff, just no guarentee that it will stop any problems.

Seems like the toyota stuff is the favourite.

Chuck that stuff in levey, or go the castrol if you are a tight A**E.