My '94 V-6 Toyota T100 truck uses, according to the manual, 5-30 below 60 degrees F ambient, 10w30 above. After reading MANY of these postings, I need to ask: considering the advances in oil chemistry, isn't 5w30 good for year round use? I have about 100K, so pure synthetic is out, but 50/50 is doable. Advice, please?