If you are at 277K miles and have the original transmission with the original transmission fluid DO NOT change it. Does this tech at the oil change shop work at Jiffy Lube and under the age of 20? He doesn't know what he is talking about. Listen to your mechanic!You should change your transmission fluid every 45K miles, but if you get over 100K miles and you have never done it, changing it will do more harm than good.People can give me thumbs down all they want and you can do what you like, but I guarantee you will mess up your car if you do it.