DOT 5 was spec'd when the HMMWV ( Hum vee ) was in the concept phase and it's still used in the the HMMWV series DoD wide today.

 

Just what I would suspect from the DoD. For the longest time they still speced MIL-H-5606 hydraulic fluid which it highly flammable in helicopters.

 

I don' theen so. It was originally, but that's old news.

There's a forum just for military vehicle owners where this has been discussed a bunch. (steelsoldiers.com) Somewhere around there someone has posted the military equivalent of the tech bulletin telling how to properly flush the DOT5 out and replace it with DOT3.

 

Someone is trying to scare you with that "highly flammable in helicopters thing". If you dig into it a little further you'll find that H-5606 is no more or less flammable than any other mineral based hydraulic oil. You'll also find that it's in use throughout Military and Civil Aviation world wide in application where synthetic rubber seals are in used and good cold weather performance is needed.

 

When you factor in that DOT 5 is two to three times the cost of DOT 3 and is not available at every big box store in the country I can see why some people would want to replace the DOT 5 in their surplus vehicle with DOT 3 just to make their own personal logistics easier.

Over the next couple weeks I'll look around for MWO's and Safety Messages requiring flush and change from DOT 5 to DOT 3 in that last couple years.

In the meantime hear's an interesting Military study on Silicone Brake Fluid and ABS for Future Combat Vehicles. https://events.esd.org/wp-content/up...quirements.pdf

 

That's about right! The guy that told me that was a door gunner in "Nam" and was scared of everything! That was a long time ago and he's still not right in the head.