Who said I didn't? But you still refuse to acknowledge the point that
an oil leak could develop that you or your mechanic DO NOT KNOW ABOUT
and you are taking a risk. And as you said, Rapco (and others) already
know how to fix the problem.

Listen: the vacuum pump has an open frame between the drive
input and the pump itself. Oil has to get into this space to get past
the pump's seal. Oil getting into this space is also going to be
apparent as a mess on the engine, inside the cowling, on the belly, and
on the ground. I work on these things every day (I suspect you don't)
and I won't tolerate leaks that present any hazard to any component.
The oil coming off the engine crankcase breather is bad enough for me.
Oil ruins wiring harnesses, air hoses, steering rod boots, ignition
leads, magnetos, alternators, and vacuum pumps. Get ready to spend more
money.
Some people won't take advice and suffer the consequences,
wondering why the bad stuff always happens to them. I spent 12 years
remanufacturing air brake components for heavy trucks and industrial
machinery, and most of the warranty comebacks followed the same
pattern: control valves full of dirt, compressors destroyed by dirt
getting past old filters or through a lack of oil pressure when the
mechanic used a bunch of silicone to seal a fitting, thereby plugging a
gallery, or chunks of rubber from rotten hoses fouling things up. The
same things happen to aircraft vacuum pumps: dirt, carbon in the hoses
from the last blow-up pump, bits of rotten hose liners, ancient and
crumbling relief valve filter media, or oil from unrepaired leaks; all
stuff allowed into them that has no place there. We used to put
instructions in every box, with every air brake component, telling the
mechanic what to watch for if he wanted the thing to work right the
first time and for a long time. It was a free education that most
refused, and we were forever trying to convince them to clean up the
factors that caused the failure of the original component and
necessitated the replacement in the first place. They just kept
replacing stuff, usually at our expense. They didn't gain much respect
as mechanics.
What killed your original vacuum pump? You seem to be missing
the point that a successful seal that would keep oil out of a pump is
the sort of seal that would need oil to keep it alive. The vacuum pump
seals are designed to run dry and are not the type of seal that can
keep significant quantities of oils out. Seal technology is a whole
science of its own, and there is no single seal that can cover all
possible applications.
Aircraft maintenance includes making sure there's a good air
cleaner to keep dirt out of the engine. It should also include making
sure oil leaks aren't bothering your pump.
Dan