I just read the Motor oil 101 to 109 here on BITOG and if I understood correctly what he was saying, it seemed to me that he was saying that all motor oils were actually too thick at room temperature to give optimal lubrication and optimal mpg at initial start up but that 0W oils were thinner than others and thus minimized the problem. So, my question is for a 2014 Kia Forte 2.0 GDI which recommends 5W-20 or 5W-30, if I'm not doing any abusive driving or high speed driving in Arizona during the summer, would 0W-20 and 0W-30 be better choices if my goal is to achieve the highest fuel economy? Am seriously thinking about the Toyota 0W-20 as it seems to have gotten rave reviews here on BITOG and other places. On the other hand, I don't want to jeopardize the warranty either, especially if using the 0W-20 is not going to make a meaningful difference in mpg. What are people's thoughts here about this? This vehicle only has 2300 miles on it and am just about to do my first oil change. Thanks in advance for the input.