Either. Though I'd for certain go with TGMO/M1 EP before using M1 AFE. Every time I see a product that speaks about fuel economy, they likely had to make the oil a bit lighter than the usual 0W-20 grade (or equivalent weight) to get that extra 1% fuel mileage for advertisement reasons. At least from what it seems, there's a trade off between engine protection vs fuel economy/emissions, and to me, that isn't worth it. Because if they are actually able to get the same protection as the other oils, yet get more EPA, why the heck is it not in every oil then?
Unless you guys can show me otherwise.