I've been using Supertech ATF+4 for the last couple years, looking to see if there's a better quality option out there. I noticed Castrol's specifically mentions full synthetic and at $1 a more, I'm contemplating whether the extra cost is justified. I don't see synthetic listed on the Supertech bottle, but I am aware that all ATF+4 licensed products are made to a standard that requires at least some synthetic base stocks and a specific additive package. The general consensus has been that any ATF+4 licensed product is a good one. But are there any "better" ones out there that might possibly outperform Supertech? There must be some difference between the different ATF+4 licensed products. Curious what you guys think. If anyone knows of any good ATF+4 deals, would love to hear about them.