I have been using the Honda coolant for about 10 yrs. It is premixed 
and I checked the ingredients vs. one of the last jugs of the factory 
blue VW coolant and the first 6 were the same and in the same order. 
There were maybe 3 more ingredients that were the same listed afterward 
in different orders. It has worked great and is a readily obtainable 
option for most folks for about $20.00/ga. Having worked in a service 
department environment for the last 25 yrs. I can tell you that unless 
you are a chemist with detailed knowledge of all the ingredients in 
each of the coolants that you might combine; just don't do it! When 
they don't mix and sludge up, sometimes even multiple flushes will not 
clear it from some vehicles heater cores which can be big $$$ to 
correct. Honda coolant works great in our vans.

David Clarkson
Equipment Consultant
Southern Automotive Garage Equipment
sageautoequipment.com