Not sure what you mean by the "magic of GC" since you did not elaborate on that point. But for an oil you can buy at the store, it's hard to beat Pennzoil Platinum for performance/value, especially with a good sale or big jug @ WM. Redline is more expensive and would possibly offer better protection if the engine is run hard often. It's probably overkill for a grocery-getter. Is this for the Sienna van? I would run either of these for 10k miles or one year, especially if already out of warranty. Schaeffers 5W-20 is another very good oil to consider but more effort is required to find it sold locally. I also would not hesitate to run it 10k miles or 1 year, based on the results we have seen so far with it.
The above are just 3 more good oils for you to consider, that would compare somewhat to GC in terms of quality, based on my own results.
BTW, I'm not seeing 5W-20 or 0W-20 listed as recommended for your Sienna on an updated list that I have access to. It seems that 5W-30 is still recommended on the application guides too.