On Thu, 15 Mar 2018 10:45:10 +0000 (GMT), "Dave Plowman (News)"
wrote:


So to the question. Is there a best oil to use for this,

Generally any light oil should do. ISO VG (SAE 30) is the oil used to
impregnate Oilite bearings during manufacture.

and how to soak
the bearing bush? I'm assuming it is a porous type which soaks up oil.

The best way is to get a discarded fridge compressor in working order
and a fairly robust glass jar with a tin lid. Jam jar is usually OK.

Connect up the compressor and find which pipe is out and which in. To
the jam jar lid solder (soft solder is fine) a piece of metal tube of
same/similar OD as the fridge compressor inlet tube.
Use some reinforced plastic tube to connect the jar lid to the
compressor.

Try to clean as much old oil out by baking the bearing at 200degC
(domestic oven) for half an hour or so.

Part fill the jam jar with warm light oil, place the bearing in the
oils so it is fully submerged, fit lid to jar and turn on compressor
to extract air. You will see bubbles rising from the bearing
material. Hold vacuum until bubbles stop, release, wait 5 mins and
repeat cycle several times. On the last cycle leave the bearing in
the oil for an hour after finally releasing the vacuum.

Glass jars are fine under vacuum but (obviously) not pressure. The
fridge compressor makes a fine vacuum pumps and no pressure switch is
required as the high pressure outlet is simply open to air.