He buys the oil and brings it to the dealer.  Many people did that in
the 1970s with synthetic oil, which was rare on the retail market back
then.  But don't bother with special transmission transmission fluid
because transmissions can be far more particular about their lube than
engines can, so just use what's recommended by the factory.

7500/6 is nothing special for oil, and even 20 years ago many car
makers were recommending that change interval for conventional oil that
was much worse than what's sold now.  Go to www.api.org for information
about oil quality, but for viscosity information refer to the owner's
manual.

No! It should be _prohibited_ by the manufacturer because all their
approved oils have fine diamond dust mixed in with them to make the
engine wear out faster so you'll have to buy a new car sooner.
Furthermore Saddam Hussein was only weeks away from attacking the U.S.
with his WMDs in 2003, and George W. Bush served gallantly in Vietnam.

Rudy is an Amsoil dealer I believe.  The test is known as a "used
oil analysis", which measures the levels of various wear metals
and other substances in the used oil.

Honda doesn't necessarily "approve" motor oils except for their
own labelled oil at the dealer.  What they use in the US is made
for them by ExxonMobil.  I would suspect that it's probably just
one of ExxonMobil's off the shelf formulations repackaged with a
Honda label.  I doubt they would have them make a specialty
formulation and go through the six figure expense of running all
the sequence tests needed for API certifications.  They'll just
piggyback on something like the Mobil Clean 5000 tests.

A lot of oils blenders save on costs by simply buying an additive
package and base oils from known suppliers.  The additive companies
have already run the full sequence tests for the API SM standard
with a blend of their additive package along with a certain grade
of base oil.  So anyone who blends a pretested additive package
with certain grade of base oil can submit the test data from the
additive company for API approvals.  This makes it easy for some
smaller companies to market a product in smaller volumes without
the expense of development and/or testing costs.

The additive companies stay in business by selling these pretested
additive packages.  The big players in the market are Lubrizol and
Infineum; Shell and ExxonMobil also develop additives.  They also
sell components as well as develop additive packages for some of the
larger marketers.  While it might not make sense for Lubrizol to
develop an additive pack for a small player like a supermarket house
label, they have been known to create specialty packages for large
companies (like Quaker State).

He uses an Amsoil brand filter - probably manufacturered to
Amsoil specs by Baldwin filters.  There is no manufacturer's
approved list in the US, save perhaps the OEM filters you can
buy at a dealer.

I'm assuming you live in the US or perhaps Canada.  Some
European countries have stringent requirements that cars must
be maintained by licensed mechanics.  The rules even state that
maintenance parts and fluids must come from a manufacturer's
approval list.  My Italian manager tells me that a list of
allowable tires is listed on registration cards.  Such rules
wouldn't be allowed by US federal and state laws.