Use teflon encapsulated  silicone O-rings for
both oil and water seals. Use at least silicone water hose if not AN lines or
aluminum pipe. If in doubt ask on here as someone has tried most everything.

Paul Lamar

Mike Wills wrote:

  Regarding the use of silicone hoses. Refer to this article that I was
told about this past weekend which describes the hazards of using silicone
tubing/hoses in any place where there is a possibility of exposure to oil.
The URL is:   http://geocities.com/sdrx7_club/hosetest.pdf

  The author is an M.E. who does this sort of testing for a living. He also
drives a pretty nice 94 RX7. He says that at least in the car virtually any
hose used underhood is constantly exposed to oil and is susceptible to this
kind of damage if silicone is used. He also questioned the use of the
silicone encapsulated O rings, particularly the oil control rings. He said
that he has noted some porosity in the teflon of these O rings which could
lead to exposure of the silicone core.

  I dont really know this guy well, but he appears to be very qualified in
this area. And he appears to have pretty well tested this. I'd strongly
recommend considering this before using anything that is silicone based
which could potentially be exposed to engine oil.

Mike Wills

Silicone water hoses have been used in heavy duty trucks for the past 20 years
and they appear very popular. If you have oil on your water hoses I think you
have an oil leak. People don't really care about this in a car as they are
unwilling to clean the engine let alone open the hood but I think the situation 
is different with an aircraft engine. Tracy has been using silicone water hoses
for the last five years and 1000 hours.

BTW teflon encapsulation is also available with  Viton but the temp range
is only 300 degrees max. This is easy to test. One can boil an O-ring
in oil. I have a TES O-ring I can try it with. Not a long term test of course. 

Creavy also has a stainless steel spring core teflon encapsulated O-rings 
good to 500 degrees.

http://www.creavey.com

Paul Lamar
 
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