Well my Glass Goose is still mothballed, although I oil and turn over its RX8 engine regularly.  One day I may get it finished (need to re-retire!).  Hopefully the engine will run one day.

My beautiful 2005 RX8 Shinka with 49K miles has gone from 1-2Qt oil consumption between oil changes to 1 qt every 100-200 miles!   There are no leaks nor smoking.  The engine still starts and runs fine. My oil changes, plug changes, coil changes, etc. have all been very conservative and the engine has never overheated nor been starved for oil.

The dealership thinks the engine is mortally wounded and wants to put in a new one for $6500.  They believe that the cat converter is handling the oil leaking past the seals (for now).

Although well out of the engine (time) warranty, Mazda will pick up 1/2 the cost of the engine replacement.

I'm not sure I have a lot of choice, but suggestions are appreciated. $3200 is a lot to put into an 8 year old RX8.  I doubt I could get a more powerful, tuned engine for $3K instead of just replacing the engine with a factory-new motor.

I also wonder if I should run slightly heavier oil (maybe 10w-40) during hot Florida months instead of the 5w-20?

Scott Gettings

My RX8 has about the same millage and no problems.

Temporarily dis connect the cat and see if it smokes.

It may be the metering pump has failed.

Next test is take the metering pump off, block off the metering pump hole,
and mix one ounce per gallon and see if the oil level in the pan decreases.

It is rare that the side seals on the rotor leak ever since Mazda went
to a higher temp oil O ring. They may have gone back to a cheaper O-ring.

If the engine has good compression take it out and replace the
rotor oil rings with teflon encapsulated silicone.

Good practice for your aircraft engine :) It comes apart in a half
hour. If you organize the seals and  put them back where they came from
you wont' need new seals.

One of the secrets is if you reuse the old oil scraper rings
they must be spotlessly clean inside and out. Soak them
in carb cleaner for a few days. If you use new scraper rings
this will not be a problem of course.
The second thing to watch out for is don't nick the
rotor wall between the two scraper rings when you remove them.
Very very important!!

These can be the same or just a little more than the
stock oil O-rings from Mazda.

The proper 13B oil O-ring sizes are: The RX8 might be different.

0.093" section 4.68 inch ID
0.118" section 4.33 inch ID

I can vouch for the quality of the Creavey O-rings but some
of those water TES o-rings from Mcmaster Carr I have seen
are not as good. This is not to say they won't work. They just
don't look as good around the joints as Creavey O-rings.

Viton is good only to 400 degrees F. The center of the rotor runs
as high as 500 degrees F. I think 400 degrees F leaves's too
little of a safety margin when 500 degrees F is available
in TES O-rings at the same price probably.

http://www.rotaryeng.net/O-ring-size2.html

I just thought of something. The side exhaust port may be overheating
the stock Viton oil o-rings in the rotors.


Paul Lamar



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