[StealYourFace]

I have to bleed my brakes for an upcoming hpde. I always do the whole system before my first hpde of the year, and a partial before the ones that follow that year.

So I found a 75% full bottle of Pentosin dot 5 that I put into a ziplock bag. The bag appears to be air tight.

I wish I had a moisture tester for the stuff.

I will likely just spring for new stuff but wondering you opinions.

[vasillalov]

nope. get new bottles.

[feuer]

When you are pouring brake fluid into the reservoir, when you open the reservoir to check the fluid and even when you open the nipple to bleed the brakes the brake fluid gets exposed to air. Therefore don't assume that opened bottle is contaminated if was stored sealed and in pretty much air tight bag as you stated. If you left the container open on a shelf for prolonged time then yes, don't use it. Otherwise, I would used it, and have had used it with out any doubt in my mind.

[StealYourFace]

That settles it, a definite maybe

( think its a good excuse to buy an inexpensive tester

[techwhiz]

OP - Are you mixing Dot5 with Dot4?? Nooooooo.
Actually most Dot5 is stuff you don't want to use unless you fully flush the lines.
It's typically synthetic and has much different characteristics than Dot4.

[Jeff@TopGearSolutions]

If you just need to do a quick bleed it's fine but long term I'd go with a full flush and re fill eventually. I'm a bit of a "Brake enthusiast" so I was actually torn between the same issue the other day. I ended up putting some old brake fluid in my car and went ahead an ordered some fresh motul from our supplier cause I just couldn't cope with the fact that the fluid had moisture potentially LOL.

[StealYourFace]

I went an got a fresh bottle. Pentosin LV 4 dot 4 fluid. Same as the last stuff.