Why is the color so important? Blue, Green, Orange? Which one is the best and what is the difference? I bought one from Pepboys last week and it is BLUE.

 

Ghost Buster Slimmer green, I've found it to work better than regular green colors. I wouldn't be caught dead putting dexcool or dex compatible in my cars.

 

There is a significant difference with the orange. It is called Dextrol and is only meant to be used in GM cars. I used it my 96 eldorado and in my 2005 CTS sedan. (If I am mistaken feel free to correct me!) Nissan is bright green and I'm guessing here but, I think they may color coded them according to application. If you really want to be sure just buy Nissan antifreeze. It's not that much more expesive and you won't have to worry about having the wrong one.

 

were....you WERE a Chevy/Cadillac guy, lol

 

Dexcool, and other companies besides GM used orange although GM may have been the only true Dexcool orange supporter. There was a huge lawsuit against GM/dexcool for the stuff eating head gaskets. Long life yes, but at a cost.

Green is becoming more and more difficult to find. Walmart pretty much only sells long life yellow which can be mixed with anything. Too many idiots buying the wrong thing and messing up their cooling systems so they had to make a compromise. I found Menard's branded green which is just rebadged Peak. Most auto stores still sell green as well. If you buy it from Nissan, be prepared to shell out $20-30 for something that should cost less than $10.