i would have used a mercedes sensor if i thought that it was totally necassary but i read about alot of people in this forum using them and having no problems that was the main reason for me buying the ford part and i still cant see it as a ford part becouse its made by bosch and im not really cheap as to everything else on my car i always put high octane gas in it and i always have bought oem parts my car is now running perfect idles like a dream and im very happy with the FORD o2 sensor after i adjusted the fuel mixture everything smoothed out i think the shop was trying to pull one over on me but i dont know