Need hydraulic oil update

[Let'sgoflying!]

Used to be, for light piston a/c you’d be offered “5606”, that was perfect for most needs.

Now;
5606
5606-A
5606-G
5606-H
5606-J
PRF-5606
Royco 782

how are these different, what applications do best with /require each?

If you have a system containing ‘ol red 5606’ and it is recommended to switch to one of these, is a total system flush needed or can you top off with the new?

(Let’s assume the service manual says
“5606 hydraulic oil” to redirect this discussion away from legalities for the moment, more to practicalities)

 

[kgruber]

The best today is Dexron. Especially for cold weather work.

 

[Stewartb]

5606 in a one gallon can from Phillips is what I use. No suffix, but then I’ve never read the fine print.

 

[Clip4]

5606 thru 5606J and PRF 5606 specification describes the characteristics and provides the requirements for a petroleum base hydraulic fluid. The difference is the cleanliness for hydraulic pumps.

5606J Aviation Hydraulic Fluid meets the cleanliness requirements for "super clean" hydraulic fluid for use in modern aircraft hydraulic systems. X/C 5606A Aviation Hydraulic Fluid is recommended for use in hydraulic systems that do not require a "super clean" fluid. Both fluids are dyed red for identification and leak detection purposes.

Royco 782 is synthetic, fire resistant, with a wider temp range

 

[FORANE]

Royco 782 is synthetic, fire resistant, with a wider temp range

If you have a system containing ‘ol red 5606’ and it is recommended to switch to one of these, is a total system flush needed or can you top off with the new?

Royco 782 literature states it is completely compatible and may be topped off.
I converted to Royco 782 for the advantages stated above. Much higher flash point...

 

[Craig]

MIL-PRF-83282 is backwards compatible with 5606. Royco 782 is one brand on the market. No flush required, unless you want to do a complete fluid change.

 

[Let'sgoflying!]

“superclean”?
Any non-superclean 5606 Ive bought looked “pretty dang clean” - are we talking about dissolved, invisible unpleasantness like… water, minerals ?

 

[Clip4]

“superclean”?
Any non-superclean 5606 Ive bought looked “pretty dang clean” - are we talking about dissolved, invisible unpleasantness like… water, minerals ?

Paraffin (wax) that would affect flow rate and performance at low temperatures.

 

[unsafervguy]

The best today is Dexron. Especially for cold weather work.

And completely illegal to use in standard catagory aircraft.

 

[Plano Pilot]

The best today is Dexron. Especially for cold weather work.

Funny, my boat has a hydraulic steering system and it recommends 5606 and says you can use Dexron not in cold environments. It was built back in the early 80's so Dexron has probably changed. 5606 has always worked well.

 

[Stewartb]

What is it that makes anyone think 5606 isn’t good in cold? My hydraulic skis and brakes work fine at -40°. No hangar. No problem.