Can - Worms - Open...
The guy my lawyer hired was ready to testify
that the fully synthetic nature of Amsoil is not
good for endurance use in motors. Fully
synthetic oil does not dissipate heat. While its
much, much more lubricating the flexing of the
rotating metals inside the block still create heat.
In my case, after a 12hr drive the bottom of my
4.0 bacially became molten and the oil itself
flash-varnaished throughout the block... at 60
mph... on a friday afternoon... at rush hour...
Eastbound on Rt50 in Annapolis... in 100d
heat... It took me 6hrs to get home, more than
$4000 that i did not have to repair the truck,
which ultimately led me to choose between
losing my job, house or paying the lawyer for
the lawsuit against them...
The REASON I HATE Amsoil is because the
assholes who run the company refused to honor
their own warranty stating "since your jeep was
not factory filled with amsoil there is no way to
determine it was our product that led to the failure
of the motor... blah, blah, blah..." and they were
not customer friendly about it. The woman I talked
to (repeatedly) gave me the impression that it was
my fault for being stupid enough to use their
product.
But to answer your main question I think people who
like them are the same people who think 150d
thermostats and nitrogen tire air are performance
enhancers - they think because they are "Fully Synthetic"
and Mobil 1 is only "Half Synthetic" they 'must' be a
better oil... which is not the case. There are reasons
long endurance racers (F1, Nascar, World Rally) dont
touch the stuff (and its not because of sponsorship -
i mean have you ever known a race team to refuse to
use a product that would literally help them win races?)
Non endurance racers do use it because there is no long
term heat buildup in their motors (drag racers, short
track) because of the benefits of the reduced friction.