> Maybe I'm mistaken, but I believe the 5W-50 Syntec is also 100% true
> synthetic, and they have or used to have a 20W-50 that I also believe was
> 100% synthetic

There was a big controversy about this a couple years back. Castrol had
been using real PAO synthetic base stocks for their Syntec oils, but then
changed to VHVI base stocks, because they're cheaper. VHVI base stock is
not synthetic, and contains all the waxes and other undesirable ingredients
that refining petroleum cannot completely remove. Castrol continued to call
their oils "synthetic" on the grounds that the additives to the base stock
were synthetic. Mobil had a fit about this, because Mobil 1 uses real PAO
base stock and they didn't like Castrol marketing their Syntec as synthetic
when it's really not. The matter went to arbitration before some marketing
authority, and Castrol won. Even though Castrol won on marketing grounds,
Syntec does not use PAO base stock, and contains all the undesirable junk
that comes with dino oil and which true synthetic avoids. Any American-made
Syntec does not use PAO base stock, and is not truly synthetic. The German,
5W-40 does use PAO.

While we can debate the merits of dino versus synthetic oil, I think we'd
all agree that if you're buying synthetic oil, it ought to be real, honest
synthetic oil. So, I quit using Syntec and went over to Mobil 1 in the
V-Dub, and went to Amsoil in the van. Plus, Mobil 1 0W-40 has the VW 502.00
rating, so, what the heck.