I was under the impression that my 2002 Ford Ranger used Green coolant but now that I read more into I am seeing that it takes yellow. The sticker on the radiator showed green fluid so i got confused when reading up on it. I see Green and Yellow are not supposed to be mixed and the coolant that was in the vehicle was green. Is this going to mess up the vehicle? Should I flush and refill with Yellow Coolant or is the Green ok?

 

My chart shows that 2002 was the first year that the Ranger got G-05 coolant instead of the traditional green. What does your owner's manual say?
ANYWAY, you could use either green or G-05, it's just that you really can't mix them. The G-05 is a long-lasting coolant, the ethylene glycol green should really be changed out every other year. My pick would be to have your system thoroughly flushed and install G-05, which is probably what should be in there anyway. Just don't let somebody at an Iffy Lube add a 'who knows what" type of antifreeze to it ever again.
BTW, If you go to a store and buy an "all makes-all models" antifreeze, it's just a rebadged DexCool, so it's best to avoid that.