Best brake fluid

[brockdeck]

Cheap fluid, its almost all the same. Supertech, generic, expensive brand name, I doubt you will tell a difference if it is all fresh which is what actually matters. It almost all comes from the same place. I roll with the cheap stuff, truck stops great. Marketing goes a long way doesn't it?

 

[Rifleman]

I'd use any one of the generic Dot 3 brake fluids sold at an auto parts store, but at a minimum, I always do a complete brake fluid flush/change every 2 years or less. I'll do the flush/change sooner then 2 years, if i start to notice the color of the brake fluid in the master cylinder change from clear, to a honey color.

 

[sunrk]

I use Bosch/PBR brand DOT-3 but we also get Nulon branded brake fluids and various other brands. Most brake fluid in Australia is all made in the same place by a big chemical manufacturer and the only different is the dye colour used.

 

[flintknapper]

The best is fresh, we use cheap DOT3 and change it often.

^^^^^^ Agreed!

This will be your best advice whether running DOT 3,4,5.1 (any of the Glycol Ether) based fluids.

Rule of thumb would be every two years under normal use.

Glycol Ether based brake fluids are hygroscopic (attract moisture) and will need to changed for that reason alone.

Also the corrosion inhibitors break down over time. 'Color' of the fluid is not necessarily a reliable indicator of when to change it.

Both the 'wet' and 'dry' boiling points between DOT-3 and DOT-4 are minuscule. You have to move up to DOT 5.1 to realize any significant gains.

 

[flintknapper]

I used Valvoline DOT 3+4 synthetic brake fluid. From what I understand, synthetic fluid does not absorb water which causes corrosion as with normal brake fluid. Also, since there is no water present, the fluid cannot "boil" and cause brake fade under hard usage.
DOT 5.1 should be even better.

First...the term 'synthetic' is broadly and loosely used in the industry and especially in advertisements. The word/meaning 'synthetic' can refer to a minimally advanced refining process (as with semi-synthetics) to an actual scientific 'building' of a product (through polymerization) to create fully-synthetics.

But...in no wise should the term be diagnostic of a products tendency (or not) to absorb or attract water. What determines that is the Base material. Currently ONLY the silicone 'based' fluids are hydrophobic (repel water).

DOT 3,4,5.1 are ALL Glycol Ether based and DO attract moisture.

As for water/moisture in the system...it is fully 'expected' that this is going to happen over time with DOT 3,4,5.1 brake fluids. To that end...they have established two tiers of boiling points.

1. Wet boiling point (fluid with a certain ratio of absorbed moisture).
2. Dry boiling point (fluid non-contaminated).

For instance:

DOT 3 fluid........(Wet boiling point 284° F.) and (Dry boiling point 401° F.)

So....you can easily see why we would strive to stay as close to the higher Dry boiling point as possible.

Your last summation '5.1 should be better' is correct. It does have a higher boiling point.

 

[Cruzerman]

Again, all will work. But I fail to see any reason to use DOT 3 over DOT 4. DOT 4 has higher specs, is pretty much just as cheap, and is compatible with DOT 3. If you are on a trail and your buddy only has DOT 3, you can add it to your DOT 4 without issues. Why would you use DOT 3 is beyond me. That being said, it will work just fine.

 

[ZackR]

This stuff is cheap, commonly available and works well. Change it every 2 years, easy as that.

 

[SmokingRocks]

Again, all will work. But I fail to see any reason to use DOT 3 over DOT 4. DOT 4 has higher specs, is pretty much just as cheap, and is compatible with DOT 3. If you are on a trail and your buddy only has DOT 3, you can add it to your DOT 4 without issues. Why would you use DOT 3 is beyond me. That being said, it will work just fine.

While I agree I struggle to see when the higher spec of the DOT 4 fluid would be needed for our rigs. I don't even touch my brakes when I coast down from the Eisenhower tunnel 8 miles down a 7° grade. Cheap bulk dot 3 is what I choose.

Perhaps for towing... But even at that a good driver is going to downshift rather than ride the brakes. Any of you doing autocross competitions with your 80's?

Rule of thumb would be every two years under normal use.

Preach brother ^

Change the fluid every year under heavy use.

IMO this includes regular wheeling as exposure to excessive dust and water is common

 

[Dave 2000]

DOT 3 has virtually disapeared here, DOT 4 is all you will typically find. Strange that DOT 5 is freely available, and yet 5.1 (backward compatible) is not seen on the shelves?

I have DOT 4 in mine, change every couple of years......job done.

Regards

Dave

 

[Boing]

Because of offroad endurance racing we learned that the wet boil is the only number that really matters for for longevity with water in your life ... Amsoil makes a "3&4" that has a silly high wet boil of 368 (F), all of the racers that have used it have had nothing but good things to say, its considered normal to dump the fluid at least every two years if not sooner...

 

[flintknapper]

DOT 3 has virtually disapeared here, DOT 4 is all you will typically find. Strange that DOT 5 is freely available, and yet 5.1 (backward compatible) is not seen on the shelves?

I have DOT 4 in mine, change every couple of years......job done.

Regards

Dave

I'd wager that most folks that stock DOT-5 don't know that it is a Silicone based fluid and also that it should not be used in vehicles with ABS.

They probably assume because of it's designation DOT (5) that is the next progression from 3 & 4 and still a Glycol Ether base (which it is not).

 

[sxp]

Dot 5 is common in military vehicles. It will eat seals, and cannot be used in a system that had 3, 4, or 5.1 in it without a serious clean out. I ran it in my '67 M715 after I rebuilt the entire brake system. Good stuff, a bit squishy, but great for vintage rigs.

 

[Dave 2000]

I'd wager that most folks that stock DOT-5 don't know that it is a Silicone based fluid and also that it should not be used in vehicles with ABS.

They probably assume because of it's designation DOT (5) that is the next progression from 3 & 4 and still a Glycol Ether base (which it is not).

Very possible, never asked but will when the rep comes around, he is happy to sell anything that ups his commission, unless you know what your talking about

Regards

Dave

 

[Tools R Us]

I'd wager that most folks that stock DOT-5 don't know that it is a Silicone based fluid and also that it should not be used in vehicles with ABS.

They probably assume because of it's designation DOT (5) that is the next progression from 3 & 4 and still a Glycol Ether base (which it is not).

Yep, DOT 3, 4, 5.1 are hygroscopic, some act like that is a bad thing? In the past oil based was used, living on the water planet, it's unavoidable. In that type of fluid, water stays as droplets, puddles in low spots, like the calipers, making it very hard to remove. When heated, at about 212F, it turns to vapor, instant soft or no pedal. The change to hygroscopic was because moisture is carried in the fluid, slowly reducing the boiling point and making it much easier to flush out. So it's a good thing, but we are back to fresh fluid is better than old fluid, all of the types require maintenance.

Is 5.1 better than 3, yep it says so right on the bottle! When you go the the gas pump, it says right on the sticker that premium is better. If you motor isn't tuned to take advantage of higher octane fuel, you are just wasting cash, no other benefit. The '80 brakes do a good job of dissipating heat, high void area rotors, etc, DOT3 is spec for it, decades of abuse have shown that it works well. If we were talking stock cars at Martinsville, it would be different!

Any of it will work, run what you like, but for best performance and part life, keep it fresh. Personally I run the cheap stuff. Suck the reservoir dry and refill a couple of times a year and fully flush at each brake job is good practice. Clean it up before it looks like this!

 

[flintknapper]

Yep, DOT 3, 4, 5.1 are hygroscopic, some act like that is a bad thing? In the past oil based was used, living on the water planet, it's unavoidable. In that type of fluid, water stays as droplets, puddles in low spots, like the calipers, making it very hard to remove. When heated, at about 212F, it turns to vapor, instant soft or no pedal. The change to hygroscopic was because moisture is carried in the fluid, slowly reducing the boiling point and making it much easier to flush out. So it's a good thing, but we are back to fresh fluid is better than old fluid, all of the types require maintenance.

Yes, funny when you think about it. The use of a hygroscopic fluid is a two edged sword (if proper maintenance is not adhered to). On the one hand....it can be argued that a substance that 'attracts' water would not be good to have in your brake system. And were you to consider that property ONLY...you would be right. BUT....that same fluid also 'absorbs' water (the two being miscible). A very important aspect for the reasons you cited.
I.E. the water is dispersed (not pooled) in the system. Of course, there is a high end to this singular advantage.

The property that allows the fluid to pick up the water is ever at work, so eventually you get 'too much of a good thing' and end up with a dilute solution. Since we live in a world where there is moisture in the air we breath...it is a forgone conclusion it will find its way into the brake fluid. So your sage advice to keep 'fresh' fluid in the system is the most important thing we can take from the conversation.

Now that everyone knows so much more than they ever wanted to about brake fluid, change the damn stuff once in awhile!

That one picture you posted is grotesque. Looks more like a spittoon than a MC reservoir.

 

[BILT4ME]

Yep, DOT 3, 4, 5.1 are hygroscopic, some act like that is a bad thing? In the past oil based was used, living on the water planet, it's unavoidable. In that type of fluid, water stays as droplets, puddles in low spots, like the calipers, making it very hard to remove. When heated, at about 212F, it turns to vapor, instant soft or no pedal. The change to hygroscopic was because moisture is carried in the fluid, slowly reducing the boiling point and making it much easier to flush out. So it's a good thing, but we are back to fresh fluid is better than old fluid, all of the types require maintenance.

Is 5.1 better than 3, yep it says so right on the bottle! When you go the the gas pump, it says right on the sticker that premium is better. If you motor isn't tuned to take advantage of higher octane fuel, you are just wasting cash, no other benefit. The '80 brakes do a good job of dissipating heat, high void area rotors, etc, DOT3 is spec for it, decades of abuse have shown that it works well. If we were talking stock cars at Martinsville, it would be different!

Any of it will work, run what you like, but for best performance and part life, keep it fresh. Personally I run the cheap stuff. Suck the reservoir dry and refill a couple of times a year and fully flush at each brake job is good practice. Clean it up before it looks like this!

What do you use to suck out the fluid from the reservoir? I want to pick up the correct "tool" and have it dedicated to this and not end up crossing it to sucking up oils.

 

[ZackR]

What do you use to suck out the fluid from the reservoir? I want to pick up the correct "tool" and have it dedicated to this and not end up crossing it to sucking up oils.

This is what I use to clear out the brake fluid reservoir. I store it in a gallon zip lock bag with other "brake fluid" stuff like my one man bleeder.

 

[SmokingRocks]

I use a turkey baster I 'borrowed' from my wife's cooking gadget drawer... She was so happy that I was maintaining something as critical as the braking system that she was ok with it... at least that’s the way I remember it...

I added a 6" long silicone tube on the end to help get to the nooks n cranny's.

 

[Tools R Us]

What do you use to suck out the fluid from the reservoir? I want to pick up the correct "tool" and have it dedicated to this and not end up crossing it to sucking up oils.

We use a cheap turkey baster, yep, needs to be dedicated, don't want oil contamination. They need to be washed after use, or the brake fluid can ruin the bulb. If the reservoir is really gross, like the one above, had like a 1/4' of goo, we snatch it off and wash it.

 

[Dave 2000]

In the trade it is common knowledge that the colour of the fluid changes in relation to water content, a quick glance tells you whether you should get out the moisture content tester, of course we don't know if customers have had the turkey baster out , any doubt and we get the tester out. If moisture content is greater than 1%, it goes on next years service schedule, if 2% I bleed the system through.

Unfortunately brakes systems do not exchange fluid during operation except when putting in new brake pads, i.e. when fluid gets pushed back up the lines into the master. So changing the reservoir contents may well help visually/psychologically but is of limited use, water being heavier than brake fluid it falls to the lowest point in the system..........i.e. the brake callipers, just where you don't need it.

It is a fair bet if the content is >2% in the reservoir, then expect at least 5% or more in the calliper, there is a chart in one of the drawers in my lock up somewhere, it has the % of contamination versus boiling point, it does not take much contamination to lower the boiling point.

Change every two years, sleep well and call it done.

Regards

Dave