Elsewhere I"m listening to a discussion about using boiled linseed
oil/Tubeseal to protect against rust on the inside of the fuselage.
There appear to be two views: one is start pouring the oil in thru a
small hole until full, then seal the hole. The second view is fill her
up, slosh around to coat, drain and leave the hole open.

Is there an authoratative source for which approach to take?

-----portions snipped-----

no. it is recommended aircraft practise for a hole to be drilled
between the tubes in the centre of the area the joining tube will sit
over. that's if they followed standard practise. so you can pour in
one end and rotate the fuselage all about and the fluid will
eventually migrate through the entire fuselage.

the two fluids work differently. linseed is heated before use to thin
it out and so that you can feel how far it has reached. it needs to be
sealed off since the setting to a varnish absorbs oxygen and leaves
the interior air in the tube oxygen depleted. once it sets off it
stays in place.

tubeseal has components in it that wick out over the surface of the
metal. I tubesealed my fuselage six months ago and it still seems to
be fluid.

another method I've found to still be working after 50 years is to
swab the tubes out with lanoline (wool grease) the auster fuselages
have this and in my cutting out of a corroded part on the rudder I
discovered that the corrosion had not spread from the area that was
damaged.

I went with tubeseal when I redid the fuselage.

Stealth Pilot

This bit about sealing the tube after sloshing/draining has some
logic, but doesn't it seem to be a conflict when we leave a drain hole
at the base of the four struts, at the bottom of the landing gear, in
fuselage tubing, the horizontal stabilizers and elevators, and the
rudder? - MikeH

There are no holes are left to the outside of the metal frame, when the work
is complete. In addition, all of the tubes should have become completely
coated on the inside and all will have been drained--none are left full.
IIRC, the outside is treated for rust prevention after the inside has been
drained and sealed. Remember that the location of fill and drain holes does
have some structural implications, and that some locations may be difficult
to keep clear for the subseqent filling and draining.

As to exactly what to use and how to use it, I would recommend joining an
EAA chapter and attending their meetings and functions. There are a lot of
mechanics and restorers, in addition to builders, who are members and who
are quite knowledgeable and experienced in this sort of work--however,
relatively few of them read usenet and fewer post.

That availability of knowledge and experience is one of the strengths of the
EAA Chapter organization--otherwise you would need to apprentice as a
mechanic to gain that type of knowledge.

Peter