OK, yeah, the page is here:
https://www.exxonmobil.com/en/basestocks/products/group-ii-base-stocks
And for the EHC45/65 products:
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Looks like you can really slash Group III use for the 5W-30, but it's a much smaller savings with the 0W-20.
If you are dropping dexos, for the 5W-30 you can go straight EHC and still be API SP/GF-6 (and I assume API SQ/GF-7).
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This does at least illustrate how much of a step-up dexos is from the basic API approvals.