Is it harder to get a good pedal with dot 5 fluid? My first experience with it and I was wondering if it is normal to have a spongy pedal. Car it new to me and the PO put it dot 5 with all new stuff. The pedal just doesn`t feel good to me though. It almost feels like the master cyl is bad. I`m going to try bleeding first.

I run it with no problem.

Is all Dot 5 purple in color?

dot 5 get can get air trapped in it giving a spongy feel. if the master cylinder has a small piston there will be more travel. I've been using dot 5 for decades with no issues and it does have a purpleish tint.

you have to be careful when you are bleeding it in a new system or you cause "foaming" while you bleed it, churning up air as you pump.

that may be what you are feeling. or just the new to me car thing where it feels weird.

if it stops and the pedal doesn't go to the floor, you are probably ok.

The pedal doesn`t feel hard and the pedal drops more once stopped.

I think that's a bad master cylinder.

If the pedal drops while holding it down then you have a leak somewhere.

I'm running DOT 5 in my Coronet and have never noticed any pedal difference over DOT 3.

Oh gosh, I just love this topic!

This will feel and act just like any other brake fluid. If it does, its not the fluid.

So many rumors and bad info on this stuff abound around here that I find it amazing.

Use it, it works great.

SportF, I don`t think anyone here was saying Dot 5 feels any different but I was asking because I have had no experience with it. It is already in the car from the previous owner and I am experiencing issues so i wanted to rule it out. That`s all.

Not criticizing you mopars4ever, but a comment in all the wrong beliefs in the stuff.

Air is entrapped within easier, especially at elevation (defies physics)
Can't use it when racing because it will get too hot
Can't mix with other fluid, will cause system failure (its killed millions world wide as a simple result of unable to read the English)


Others can come up with the rest, this is what amuses me.


If it was possible to misuse this and cause failure, would anybody sell the stuff due to the legal liability?

I have been using it since it came out 30+ years ago.

This stuff is used extensively by all branches of Military. It is good stuff. Use it.

There is a form of it used in a recoil system on at least one big gun system.

Just my 2 cents on what I have read over the years. First off, I use it in all my classic cars, so I am a proponent.

DOT5 should not be used in an ABS equipped system due to foaming, so I would agree it is not 1:1 replaceable for other fluid types.

Back to the original symptom, does sound like a bad master with fluid leaking by piston.

Yea, I kinda felt it was the master cyl even though it doesn`t appear to be too old but it looks like a rebuilt one not brand new. I will check it out tomorrow. Thanks

I brought some DOT 5 to a register at a parts store once and the guy behind the counter freaked out on me.

Parts Guy: "What are you putting it in?"
Me: "A 1972 Dodge."
Parts Guy: "You can't use that!"
Me: "Only the best for my ride."
Parts Guy: "But it won't mix."
Me: Chuckle "The whole brake system, including lines, was replaced and I've been using DOT 5 since."
Parts Guy: "Oh, I still don't think you can use that."

Yes, it was a large national parts chain.

Ive put dot5 in 5 or 6 cars with not one single issue.

Buddy of mine put it in his 1955 Chrysler 300 and had nothing but problems with it.

He had the master cyl rebuilt by WhitePost I think.
they rebuilt it 2 or 3 times , finally told him drain and flush it out replace with dot3 or warranty was void.
he hasnt had a problem since

dot 5 will not mix with dot 3 or dot 4. they separate out kind of like vinegar and oil salad dressing. don't believe me? put both in a container together and see what happens.

I had some issues getting all of the air out of my DOT5, once I did, it seems to be pretty solid.

I couldn't agree more.