i read AEHaas's oil FAQ, and he wrote: Motor oil becomes permanently thicker with exposure to northerly winter type weather. This is more of a problem to mineral based oils. Waxes form. This is why it is a bad idea to even store a bottle of oil in a cold garage. It goes bad on the garage self just because it is exposed to the cold. is this true? how important is this? i store all my oil in my garage, which does get freezing.