Dex VI is good stuff - maybe there's better, but my opinion is that I don't know if you will see or could measure the difference. Transmissions can be finicky so I'd stick with Dex VI spec. Others may disagree. They way I see it - a GM transmission can last 150,000 miles or more in GM Dex VI. With another spec, maybe it lasts more or maybe it fails miserably. You can do your math to figure out what's best for you.