I will take a run at this.
The issue of "color" of antifreeze.
The color is a dye, different manufacturers use different colors to denote their products, or to denote different products within their lines.
That said, the "color" is not an industry standard, there are some generally accecpted standards withing the antifreeze community, but, there are some out there that do not follow the standards.
There are different types of chemistry involved in Antifreeze past whether it is Ethylene Glycol or Propylene Glycol, there are various additive packages and formulations that are added to the EG / PG and water mix that give your "antifreeze" those protective properties, sacrificial metals, Water pump lube properties etc. that you expect from your "antifreeze" then there are also supplemental Coolant additives (SCA's) commonly used for most diesel engines to prevent some of the special stresses that they incurr (cavitation)
So, normally, a color or dye represents a type of chemistry from a particular manufacturer. Normally it is not a good idea to mix chemistries. I would not assume from just a color that I knew what the chemistry of that particular AF was, especially without knowing the manufacturer of that AF.
If it were mine, I would check the manual, see what was reccomended, and drain and flush and replace accordingly. I would also be carefull that you do not decide to "halfway" follow the directions such as you decide that you want to run PG so it is "safer" then add in the SCA that was called for in your manual as it was likely not intended to be mixed with the chemistry used in formulating your PG antifreeze.
That said, if you run many vehicles, sometimes it is better to standardize across your fleet and run one fluid, that prevents incompatible chemistries from being mixed. IE, half dexcool, half standard EG. (this is what I do in the oils in my vehicles, we only run Rotella 5w40 so I only have to insure the folks are pouring it into the engine and I know which oil I should tell them too add)
If I was doing this, I would consult the AF manufacturer and get their reccomendation.
And on that front, I tend to use Fleet Fully formulated EG based AF and that lets me put that in all my vehicles and not have compatibility issues.
When I get a "new" peice of equipment, (I always buy used stuff) I tend to change all fluids and lubricants, and drain and flush and go to the "standard" that I use.
Sorry if I wandered too much, but if it did not interest you, I figure you stopped reading before you got here
