I know the bottle says, "Full Synthetic", and at $3.00/qt it's probably a decent oil*, but it is NOT a traditional PAO-based polymerized synthetic oil. The Castrol "decision"** allows Group-III based motor oils to legally be designated "full synthetic" even though they're severely hydro-processed dinosaur juice products.
*Most big name "synthetic blends" are priced that high, also use Group-III as their "synthetic" component and restrict even that to only about 10% by volume. At least with the Supertech "Full Synthetic", it's all Group-III except for the additive carrier.
**It's all in how you define "synthetic". PAO oil stocks are long chains "built" to specific lengths. The building block additive process is called "polymerization". Group-III dino oils are reformed under heat and hydrogen pressure in the presence of a catalyst to the desired chain length from the less desirable aromatic ring chains, and residual waxes not removed during initial processing. This reformation process is called, "isomerization".