At 02:33 AM 2/23/2007, mike . wrote...
>I like Mobil 1 better, a true synthetic. Castrol is, I believe,
>formulated
>from a natural base, much cheaper to do, but costs the same.

Yes, and no. The article is talking about Castrol GTX, which has always
been a petroleum based oil. You're thinking of Syntec, which used to be
a Group IV (polyalpha olefin-PAO) basestock (same as original Mobil1).

Several years ago, Castrol changed to a Group III (hydrocracked
petroleum) basestock, without any notice, and without any decrease in
price. They did it because it's much cheaper, so they make more profit.
Mobil complained to an industry advertising arbitration board (not, as
is frequently told, a court of law) that Castrol should not be able to
call it a "synthetic." The industry arbitrators, marketeers all, saw an
opportunity and took it. Now the public has no easy way of knowing what
is truly a synthetic oil (i.e. started out as something which isn't
oil), and the industry can make greater profit by selling cheaper
basestocks as "synthetic."

Group III oils are very, very good. But they're also much cheaper to
produce than Group IV synthetics. At equivalent cost, I'd stick with a
true synthetic. I simply won't buy Castrol anything anymore, due to
their disingenuous marketing. Shell Rotella T Synthetic 5W-40 is about
$15/gallon at Wally world. It's a diesel/gasoline rated Group III oil,
at a reasonable price.