Since their base stock molecular structures are radically different (and I'm guessing their add. packs are also), does anyone forsee any problems going from S2K 0w30 (in now) to Redline 10w30 or 5W-40 (this spring/summer change) and then back again next winter to Amsoil Euro 5W-40?? I'm thinking of this because I have 5qts. of Redline D4 that I cannot use, so I was going to exchange it for summer high vis, high HTHS oil and then use the slightly thinner case of Amsoil Euro next winter. Good plan, or once you go Redline, you can never look back (due to chemistry)???