I can get 20w 50, but the 15 is out. So, since I will be riding for most of the year, including a good amount of cold weather riding, will the 20 be just fine for Colorado riding (6500 ft)? Here is an accurate description of my locale: I live in a high plains desert. Low humidity, widely varying temperatures during the day (a 30 degree change in temp is not uncommon), plenty of nice steep hills and a nice elevation change from the one end of town to the other. During the summer, I will be riding in temps as high as 100 and as low as 50. During the winter, I will be riding in temps as low as freezing and as high as 60. So, before I go spend money on what could be the wrong oil, what are your thoughts about the oil I should be using?