Can I mix hydraulic brake fluid

ron sterba · #1 07-25-2014, 11:15 PM

A borrowed brake bleeder tank had some hydraulic brake fluid in it. As we filled one system RV9A we added a quart of synthetic fire resistant hydraulic fluid (782 Royco) to the tank and then filled another RV9A. These were all empty brake systems. My question is ..are the fluids ok to be mixed or do we drain the two planes brake systems? Vans sells the 782 fluid wasn't able to ask Vans technical guru's today.

Ron

jjconstant · #2 07-26-2014, 12:33 AM

milspec 5606 and the newer milspec (which is what I believe the Royco stuff is) are compatible for mixing. I wouldn't expect to achieve full effectiveness regarding higher flashpoint etc of the new stuff if is mixed...

ron sterba · #3 07-26-2014, 12:20 PM

Thanks Jerome I guess we are in the transition erra from past to up and coming of fluids that have higher flash points. Is there a place that I could read more about this subject? Sorta in the dark on this one. Thanks

Ron

Mike H · #4 07-26-2014, 02:24 PM

MIL-H-5606 was superseded by MIL-H-83282 many years ago. Last time I ordered a quart of hydraulic fluid from Spruce the stuff that I got said it met the requirements of 83282 which is also an approved replacement for 5606.

Vac · #5 07-26-2014, 07:41 PM

Jeremy is correct. Long answer is in this thread:

http://www.vansairforce.com/communit...ighlight=83282

Cheers,

Vac

ron sterba · #6 07-27-2014, 12:29 PM

Mike and Mike and Jerome. The reading was excellent on the Mil spec for the oils. The information provided is that every builder should make a COPY and PASTE on the info and file it! At some point a chapter member will ask the question about fluids. I believe this would be a good OSHKOSH forum presentation. Plus EAA WORKSHOP VIDEO! Somebody let the powers to be about this mix and what to expect. So many builders know have a half used gal of fluid setting on their workshop shelves. As I checked in the MSDS on the ROYCO 782 Hydraulic fluid there is a shelf life. A "FROM" printed date on the case of product indicates its shelf life. Was surprised at the shortness of shelf life. (Its Years but not like motor oil.) Do a search engine on 782 ROYCO hydraulic oil. ) Once you do that go back to the fine article posted by the MIKES for further listed product info websites. You'll soon come to a good understanding of mixtures in the hydraulic fluid world.

PS. moderators please store this info in the Vansairforce library.

Thanks Guys!

Ron in Oregon
RV9A