Was that oil seal red in color? If so I suspect it

is silicone. If it is red (mine is) and it is silicone it is not
 recommended
for Alphatic and Aromatic Hydrocarbons and synthetic lubricants containing
silicone. This may be the key to why Mazda does not recommend synthetic
 oil.

Is your rear oil seal leaking Tracy?

In any event a teflon or Kalrez  seal with a steel spring will be rated
to 500 degrees F and has excellent resistance to almost all chemicals.

Paul Lamar

Tracy Crook wrote:

 Mine have never leaked a drop in 1020 hours.   FWIW, the story I heard on
 the synthetic oil ban  by Mazda was that they were having warranty failures
 on catalytic converters due to synthetic oil cloging them up.  Seems it
 didn't burn as completely as mineral oil and made it through to the cats.
 I've used synthetic oil (mobile 1) for the past 900 hours so I dismiss
 stories about it causing engine or seal problems.  OTOH, I don't inject it.

snips...

 Tracy Crook
 rws@altavista.net
 www.rotaryaviation.com

Alfonso Lebron-Berges wrote:

I might be wrong but to the best of my limited understanding I
believe the so called synthetic oil is nothing else than highly
purified regular USED mineral oil (i.e.: your 10W/30 common brand)
that after use has already given up certain amount of hydrocarbons to
combustion, oxidation and degradation by heat.

If I am wrong, please correct me.

A refined petroleum oil is used to obtain the "base stock" for the synthetic, but that
is
about as close as they get.  H2O (water) is a three atom molecule.   Needless to say,
molecules are VERY TINY structures ... even the (specifically designed) long chained
hydrocarbon ones that form a synthetic.  Their extreme strength comes from the fact
that EVERY molecule is IDENTICAL.

Normal petroleum based oils have a wide variety of short chain aromatic molecules that
are quickly gone out the breather when the engine heats up, as well as many types of
long chain
hydrocarbon molecules, some of which readily bond with others ... making longer and
longer
chains (we call it sludge).  Basically though, it is a hugh mix of many, many types of
molecules.

Short distances between the atomic centers of identical molecules in a synthetic, make
for
very strong atomic bonds, that maintain a very strong "shear strength" (resisting
metal to metal).  This is typically 6 times stronger in a synthetic, even though the
oil is very thin.  These strong atomic bonds also hang in there lubricating at
elevated temperatures that would literally "smoke" a petroleum product.

Probably this is what caused the problem to the Mazda cat. converter.
Just receiving oil that wasn't burned.

Could be.  Injected into a combustion chamber, even a synthetic will burn ... just not
very well & probably not very cleanly.

Hope this helps ...
Dale Smith

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