The Hynautic owners manual calls for MIL- 0-5606 aircraft hydraulic
fluid.  I purchase it from the local fixed base operation at the local
airport.  It comes from a can that has this designation on the can.  It
looks bright red to me.  Beyond this, I know little.  Am I doing wrong
to follow the manufacturers recommendation?

Hans J. Bjarno wrote:

--
Nick Meloy
44' Custom Trawler  "Serendipity"
mulatfl@pcola.gulf.net  30 32.855 N  87 07.550 W
(850) 994-6165

Have used type A tranny fluid in mine for 8 years. No problems.
Just another dummy!!

Dick Schroder
Pan Handler Gulfstar '43

Plan for the worst, hope for the best, and never ever give up your dreams!!

----- Original Message -----
From: "Nick Meloy" mulatfl@pcola.gulf.net
To: "Hans J. Bjarno" danskviking@comcast.net
Cc: trawler-world-list@lists.samurai.com
Sent: Sunday, September 15, 2002 10:39 PM
Subject: Re: TWL: RE: Pressure loss in hydraulic steering.......

it's

for

Dick,
When I rebuilt my sterring cyl last yr I spent some time investigating
hydraulic fluids - including Tranny fluid .. tranny fluid used to be
reguarded as the bottom of the barrel - not anymore - the Dextron 3  seems
to be reguarded as pretty good stuff  - equal at least to the much higher
priced hydralic oils of 5 yrs ago - which surprised the heck out of me ..
because of its wide distrubution it is relatively cheap compared to whatever
else .... in this catagory .

 I did not look into the exotics - including aircraft fluids - so any of

the engr's may have more to say on the subject ...

So I remain - Like you - Just another Dummy

 All the Best
      Ken
      m/v Mrs. Hudson

I have a teleflex system specifying mil spec 5606 fluid. Found mine at the
local farm supply store under the title " snow plow oil" meets mil spec 5606
and pretty cheap $ at that. Called the tech folks at teleflex and they said
"if it meets the mil spec it will work fine".

Robb Firehammer
NE Wisc-almost time to haul out for the season!

it's

Dick Schroder wrote:

This is the alternate fluid that Hynautic recommends.  They state that
the mil spec aircraft fluid is better, but they are not too specific as
to why it is better.

--
Nick Meloy
44' Custom Trawler  "Serendipity"
mulatfl@pcola.gulf.net  30 32.855 N  87 07.550 W
(850) 994-6165

too specific as to why it is better.<<<<

The molecules fly in formation, which allows you to pull 7g when avoiding
PWCs.

Best regards, Robert Bryett.
Sydney, Australia.
mailto:rbryett@mail.com

----- Original Message -----
From: "Nick Meloy" mulatfl@pcola.gulf.net

Hi Nick et al,

The three main differences between 5606 aircraft hydraulic fluid and ATF are
the viscosity index of the products, the inclusion (or not) of
detergent/dispersant additives, and the napthenic base stock content.

First, most companies that produce a 5606 fluid actually make two versions:
5606G is a "superclean" product that is specified for critical aircraft
applications. 5606A (obsolete) is a non-superclean version of the same thing
some companies have renamed their 5606A products to help avoid confusion.
Texaco, for example, calls their version "Aircraft Hydraulic Oil 15" while
their superclean version is named "Aircraft Hydraulic Oil 5606G". Bringing
the product up to superclean standards roughly doubles the price without
making any appreciable difference in performance in our context. Special
handling is also required in order to maintain the superclean status.

OK, back to the differences between 5606 and ATF.

Viscosity Index is an indication of how much an oil thins out as the
temperature rises. The VI for ATF is around 190 which is actually very high.
5606 has a VI of about 370 which is incredibly high. For comparison,
synthetic motor oil is 165 to 185 VI, non-synthetic multigrade motor oil is
135 to 145 VI, and single grade motor oil is 100 to 110 VI. Keep in mind
though, a high VI is only an advantage when the product is used over a wide
range of temperatures. As I understand it, a Hynautic system will actually
experience a very narrow temperature range in recreational service.

Detergent/Dispersants are incorporated into ATF in order to keep the valve
body clean in automatic transmissions. These additives are apparently not
used in 5606. The downside to D/D additives is that they promote the
emulsibility of water in the oil. Water/Oil emulsions are bad news in this
(and most other) context so a product like 5606 that allows water to settle
out, so that it can be removed, is preferable.

Small proportions of napthenic base stock are used in ATF as a means to
cause a slight swelling and softening of the seals in a transmission. That
property is superfluous in a boat's steering system but it probably doesn't
cause any problems either.

To my mind the really telling difference is availability; ATF can be found
just about anywhere (Parts stores, Marina stores, Grocery stores, Fuel
docks, Gas stations, etc.) but if you need a quart or two of 5606 you'll
pretty much need to find an airport or an oil jobber. That's not always easy
to do.

Conveniently yours,

Alex