I am using sm Castrol EDGE 0w20 in my 2010 fusion v6. I have the new sn titanium Castrol EDGE 5w20 waiting to go in. On all the other Castrol EDGE flavors quarts not including 0w20 and 5w20 it talks about 15 grand change intervals. Why does the 20 weight not have this on bottle? No faith in the lighter weight?