Brake Fluid: cheap vs expensive, any difference?

[Angelfish]

The bottle on the left cost me $19, on the right cost me $12.  By now most of my cars have the bulk brand and everything seems to be in perfectly good condition.   
 

[oldford]

DOT4 is DOT4 is DOT4

 

Frank

[TAKerry]

I bought that same bottle of Prestone for my car recently. That 32oz. is about 3 times the amount I will need, cant imagine needing a gallon! 

[oldford]

One thing I try to do when buying brake fluid is the same as buying super glue. I buy as small a container as possible and if I keep it longer than six months, I buy fresh when I need it again. Just me....

 

Frank

[Oz Dodge 4]

2 hours ago, oldford said:

 I buy as small a container as possible and if I keep it longer than six months, I buy fresh when I need it again. 

I am still using brake fluid out of a gallon container my brother in law gave me several years ago when they moved!

I work on the principal that brake fluid being "hygroscopic" (unless its silicone) needs periodically to be replaced when in a system open to the atmosphere where it can attract water, but when sealed in an airtight container away from the air it should be fine. Been doing the same thing for the last few decades without any problems so far!

[joe_padavano]

The only downside to buying the gallon jug is water absorption over time if you don't use it quickly enough. For a complete brake system rebuild and flush/bleed, I rarely need more than one of the quart bottles.

[TAKerry]

I was under the impression that an open bottle sitting on the shelf will still absorb moisture. I live in a somewhat humid area and to me its not worth the risk. $15 or so for enough fluid to do a one time change is ok with me, and I dont have money to throw away.

[60FlatTop]

I buy mine brake fluid in quarts to be sure I have a fresh sealed container. And it's a fresh one sitting on the bench.

 

Sometimes a medical product will have the disclaimer "If you live in and area of humidity related illnesses" that's my territory!

 

 

[Angelfish]

I’ve reached the point where I buy brake fluid by the gallon and Rotella by the five gallon and do them all at the same time.  Once I’m caught up on the maintenance I should be ok for a while.

[Frank DuVal]

I too am in the humid east, so a quart of DOT 3 is as large as I buy. If I put the cap back on the quart, it is just like putting the cap back on the master cylinder. True, you can make the argument that makes the remains of the quart as wet as the fluid I would be flushing. But at least the plastic bottle didn't rust like the system on the car!  🤔

 

Someday I might get caught up enough to buy it by the gallon (and oil in 5s) to do the fleet at the same time. Great plan, but life is in the way.😞

[Oz Dodge 4]

12 hours ago, TAKerry said:

I was under the impression that an open bottle sitting on the shelf will still absorb moisture. I live in a somewhat humid area and to me its not worth the risk. $15 or so for enough fluid to do a one time change is ok with me, and I dont have money to throw away.

That might be why I can get away with it! I live in Australia, and most of my life in the country, not a long way from our "station" country, quite dry, a bit like one of you blokes living in say, Arizona or Texas.

[Larry Schramm]

With all of the maintenance I do on cars & trucks, I buy oil about 50 quarts at a time.  Modern trucks take 8-10 quarts / oil change.

 

Costco currently has full synthetic oil on sale for about $3.50/quart in two 5 quart jugs.

Edited September 15 by Larry Schramm (see edit history)

[ia-k]

I have several smaller bottles that I refill from a larger jug. My theory is even with a cap on a large jug (i.e. gallon) there is still an air space between the brake fluid an the top of the container. Filling several smaller containers from the larger one eliminates this air space and moisture contamination.

[Chry54]

i put a little plastic bag piece on the cap when i close the brake fluid bottle and then i use the rest till gone. hate to throw product away.    dennis

[Bloo]

Fresh is good. I don't keep an open container of DOT3/DOT4 over 6 months ever.

[ABear]

1 hour ago, Bloo said:

Fresh is good. I don't keep an open container of DOT3/DOT4 over 6 months ever.

Are you sure?

 

Do you purge your entire brake systems with new fluid every 6 months?

 

I don't.

 

Your MC does the same exact thing as a bottle with a cap on it, even MCs with full rubber gasket that gets drawn into the MC reservoir will eventually draw moisture from the air.. In some respects MCs introduce much more moisture than the bottle sitting on a shelf..

 

Folks are overthinking brake fluids..

 

As long as you put the cap back on the open container and make sure you tighten it, that fluid in the bottle will be good to use for many yrs longer sitting on a shelf than what is in the MC and brake system on a vehicle.

[Lee H]

On 9/13/2024 at 6:23 PM, oldford said:

DOT4 is DOT4 is DOT4

 

Frank

It is true that all DOT4 fluid must meet the same minimum specification. But just like motor oil (and practically every other fluid we add to a car), there are premium brands which exceed those requirements. Here are the minimum requirements, and following that, is the Motul PDS for their (very expensive) racing DOT4 fluid.

 

[oldford]

The stats above are simply differences in boiling points, viscosity, etc between brake fluid types, not different brands. If someone has a similar table from one brand of brake fluid to another, for example, DOT4, then that would be convincing evidence to me that price would be a reason to change brands. If higher price translates to higher quality for someone, they are free to buy whatever brake fluid they choose. Likewise, if I choose to keep my supply of brake fluid for a shorter period of time than someone else, that, too is my choice.

 

Frank

Edited Wednesday at 12:13 PM by oldford (see edit history)

[ABear]

2 hours ago, Lee H said:

It is true that all DOT4 fluid must meet the same minimum specification. But just like motor oil (and practically every other fluid we add to a car), there are premium brands which exceed those requirements. Here are the minimum requirements, and following that, is the Motul PDS for their (very expensive) racing DOT4 fluid.

OK, well, do YOU "race" your vehicles?

 

I don't.

 

Under normal driving conditions the fluids meeting "minimum" specifications will be more than sufficient, especially in ANTIQUE vehicles. Even DOT3 well above exceeds minimum vehicle specifications for vehicles built before the 2,000s..

 

Spending more just because it is rated for racing (IE high speed track/dirt) in an ordinary 30+ yr old vehicle that never will see racing speeds or conditions simply does not magically improve the vehicles performance characteristics.

 

If the vehicle was designed for DOT3, use it DOT3, if it was designed for DOT4, use DOT4.. If DOT3 is not available then use DOT4 but don't expect it to brake better or longer or perform better or last better.

[ABear]

1 hour ago, oldford said:

The stats above are simply differences in boiling points, viscosity, etc between brake fluid types, not different brands. If someone has a similar table from one brand of brake fluid to another, for example, DOT4, then that would be convincing evidence to me that price would be a reason to change brands. If higher price translates to higher quality for someone, they are free to buy whatever brake fluid they choose. Likewise, if I choose to keep my supply of brake fluid for a shorter period of time than someone else, that, too is my choice.

 

Frank

Frank, every manufacturer must at a least meet the minimum specifications in order to slap the DOT specification label on the bottle. That means from manufacturer to manufacturer that fluid in the bottle will do its duty as designed.

 

Any manufacturer touting the benefits of their fluids exceeding that minimum specification and vastly upcharging for those supposed benefits are nothing more than a marketing tool to make the company more money and lightening your wallet at the same time.

 

The one main item to be concerned about is the boiling point, and each manufacturer must provide testing proof that their fluid meets that minimum boiling point for that DOT number. Exceeding the minimum boiling point is fine, but in the case of most antique vehicles you would have to be driving awful fast or doing a lot of driving down steep long, long mountain grades to which one would reach the boiling point of DOT3 or DOT4 fluids.

[ABear]

As to the OPs original question of cost, one is non synthetic and the other is synthetic.

 

One is a "Bulk supplier" and one is a "Retail supplier".

 

Synthetics cost more.

 

Retail suppliers cost more.

 

ALL must meet the bare minimum DOT specifications.

 

HK brand is typically found in bulk farm/feed stores like Rural King.

 

Prestone is found in large and small retail stores.

[Dr B]

8 minutes ago, ABear said:

The one main item to be concerned about is the boiling point, and each manufacturer must provide testing proof that their fluid meets that minimum boiling point for that DOT number. Exceeding the minimum boiling point is fine, but in the case of most antique vehicles you would have to be driving awful fast or doing a lot of driving down steep long, long mountain grades to which one would reach the boiling point of DOT3 or DOT4 fluids.

This!

 

If you take your car on the track, with repeat hard (read threshold) braking, boiling your brake fluid is a concern. That is why for track events they insist on new brake fluid every time, to make sure there is no water in the brake fluid which can boil. For collector cars, this is a non-issue unless your going down Pikes Peak riding your brakes all the way (however, with drum brakes, you most likely will lose your brakes from over heating before you boiled the brake fluid)!

 

Robert 

Edited Wednesday at 02:08 PM by Dr B (see edit history)

[oldford]

Abear, I do not dispute anything you have said about brake fluids, but you indicate the difference in price is due to the difference in production cost. for example, packaging small quantities forces higher prices, since the cost of packaging is now a larger percentage of the total cost. What I am not convinced of is the idea that synthetic is higher quality than non-synthetic and would justify the higher cost. I'm not arguing, just looking for a reason to spend $15 for a quart of synthetic DOT4. So far, the only justification for the higher price is that Prestone costs more to deliver to the market.

 

Frank

[Bloo]

That's marketing doublespeak. It really confused me the first time I saw it. As it turns out, it's all "synthetic". Want good brake fluid? Get some that's fresh. Ask the guy at the counter which bottle he sells the most of. Buy that one, because it hasn't been sitting there for months. It's probably something cheap. If you need DOT 5.1 for track use or something, then that costs more.

 

 

[ABear]

12 minutes ago, oldford said:

What I am not convinced of is the idea that synthetic is higher quality than non-synthetic and would justify the higher cost. I'm not arguing, just looking for a reason to spend $15 for a quart of synthetic DOT4. So far, the only justification for the higher price is that Prestone costs more to deliver to the market.

DOT4 is available in BOTH Synthetic and non synthetic.

 

HK, bottle in your picture is not labeled Synthetic, it is labeled as Heavy Duty.

 

I can not find any reference that indicates that HK is anything else than non synthetic.

 

Here is one link I found for HK DOT4 fluid..

 

https://www.farmandhomesupply.com/harvest-king-brake-fluid-dot-4-1-quart.html

 

The Prestone bottle in your picture is labeled as Synthetic.

 

As far as synthetic being "better" vs non synthetic that is more of a PERSONAL CHOICE than actual real life improvement.

 

Synthetics STILL use carbon based base materials but instead of using carbon molecules from crude oil fractions, they use NATURAL GAS carbon molecule fractions. The inference is that things made from Natural gas is somehow much "cleaner". The truth is BOTH are CARBON BASED. Making the carbon fractions needed from natural gas is a much more complex and energy intensive process and that costs more money to produce the items.

 

I have also seen manufacturers tout that the synthetics have "rounder" carbon molecules as part of their claims that synthetics are better.. Carbon is carbon and molecules of carbon fractions isn't going to be any different.

 

To answer your question, non synthetic brake fluid will perform THE SAME as synthetic brake fluid as long as they are the same DOT rating. Chances are your vehicle was made BEFORE DOT4 specification and you will never notice and difference in brake performance either as DOT4 exceeds the specifications of your vehicle.

 

Unless you are dealing with a new vehicle most likely your vehicle calls for DOT3..

 

Heck, you can even still buy DOT3 brake fluid..

 

Found a gallon of HK DOT3 here..

 

https://www.farmandhomesupply.com/harvest-king-brake-fluid-1-gallon.html

 

Now one big item of concern though, in DOT4 there does seem to be two different "bases" that could possibly be used in DOT4 from some research, one is Glycol base which was used in DOT3 and below and Silicone bases which typically would be in DOT5.. One wouldn't think that is possible but apparently it is..

 

Don't mix Glycol based fluid with Silicone based fluid..

 

Make sure the label states is compatible with DOT3, if it says not compatible with DOT3 it may be Silicone based.

 

HK DOT3 and DOT4 is Glycol based.

 

Prestone DOT4 is also GLYCOL based per here..

 

https://contentinfo.autozone.com/znetcs/msds/en/US/1083028

 

So no issue with mixing glycol or silicon bases between the two.

 

If you want to spend more, buy the name brand, if you don't mind saving some money, buy the generic bulk brand. Both should work the same.

[Bloo]

It's not synthetic then if you start with one form of petroleum (crude oil) and is synthetic if you start with another (natural gas)?

 

Of course petroleum would have to be used in the process somewhere, but you might be a long way from that by the time you get to polyglycol ether. I'll admit my chemistry is weak, but how on earth did you get from crude oil to polyglycol ether without synthesizing it?

 

Silicone fluid (DOT 5.0) is whole different thing than glycol-based fluid (DOT 3, DOT 4, DOT 5.1), whether the glycol-based fluid says synthetic on the label or whether it does not.

 

SIlicone fluid is not hygroscopic, and as such does not collect water out of the air. You can keep silicone fluid a long time without degradation. There is no wondering whether the cap was airtight. It does not have the issues we have been discussing. It has different issues.

 

[Lee H]

4 hours ago, oldford said:

The stats above are simply differences in boiling points, viscosity, etc between brake fluid types, not different brands. If someone has a similar table from one brand of brake fluid to another, for example, DOT4, then that would be convincing evidence to me that price would be a reason to change brands. If higher price translates to higher quality for someone, they are free to buy whatever brake fluid they choose. Likewise, if I choose to keep my supply of brake fluid for a shorter period of time than someone else, that, too is my choice.

 

Frank

Frank, I posted that only to show the minimum requirements (example: “wet” boiling point DOT 4 minimum is 311F…Motul DOT 4 is 401F) 

 

I wasn’t suggesting that I need that high a boiling point, but only the fact that not all DOT 4 brake fluid is created equal.

[ABear]

5 minutes ago, Bloo said:

I'll admit my chemistry is weak, but how on earth did you get from crude oil to polyglycol ether without synthesizing it?

Its called "hydro cracking"

 

Hydro cracking is how we get pretty much every single thing from crude oil AND natural gas. In essence crude oil and natural gas are  run through specially built "reactors" which use combinations of heat, pressure and reactive gasses (hydrogen is one of the key reactive gassses used) which break down crude oil and natural gas into smaller and smaller carbon fraction molecule chains. The smaller carbon fraction chains are then used as feed stock to recombine into other highly useful carbon chains for many, many products. Nearly nothing goes to waste in the process, crude oil and natural gas even though they have been severely "vilified" by well meaning but highly misdirected people are the backbone that truly keeps us alive.

 

If you take ANY medicine for any reason, yeah, crude oil and/or natural gas is at the heart of that medicine as carbon molecule fractions from Hydro cracking" are used as the base for even the humble well known Aspirin tablets.

 

There are many, many items we use and need that are a direct result of hydro cracking.

 

Yeah, my Dad worked at a refinery all his life, they refined crude oil bases into food grade "white oil" bases used in food, food contact, medicine, cosmetics and more.

 

You may have heard of "Vaseline", yeah chances are that the "base" used to make it which is called "Petrolatum" is still coming from the refinery near me.

 

People don't realize that they have been using "synthetic" products for many, many yrs as it was never labeled as such..

 

Synthetic labeling came more about as a means to justify higher prices as being a "superior" product.

 

As far as silicone, while it does come from silica (which is a refined specific types of sand), they are treated with hydrocarbon fractions which came from crude oil or natural gas as part of the process to become silicone(s) that we know today.

 

If you want to know more, do some searches on products made from hydro cracking crude oil and be enlightened.

[oldford]

33 minutes ago, Lee H said:

Frank, I posted that only to show the minimum requirements (example: “wet” boiling point DOT 4 minimum is 311F…Motul DOT 4 is 401F) 

 

I wasn’t suggesting that I need that high a boiling point, but only the fact that not all DOT 4 brake fluid is created equal.

I agree 100% with you.

[ABear]

26 minutes ago, Lee H said:

Frank, I posted that only to show the minimum requirements (example: “wet” boiling point DOT 4 minimum is 311F…Motul DOT 4 is 401F) 

 

I wasn’t suggesting that I need that high a boiling point, but only the fact that not all DOT 4 brake fluid is created equal.

Unless you have a very, very new vehicle, DOT3 will be sufficient for most vehicles.

 

As a check, I looked at the manual for my 2013 Ford F250, the manual calls out for DOT3 as seen in the attached chart. I have circled the line for brake fluid specification.

 

Then I looked at my 2019 and 2020 Ford F250s, both of those specify DOT4, I am not bothering to include those here..

 

So, between 2013 and 2019 vehicle manufacturers changed over to DOT4 specifications, much of that most likely due to HEAT which is the boiling point specification.

 

Vehicles built before the switch over to DOT4 requirements will be perfectly happy with DOT3 or DOT4 and if you choose to run DOT4 you most likely will not see any difference in performance on older vehicles unless you are driving in extreme conditions like braking all the way down Pikes Peak or Sunday at the Indy 500..

 

If one is uncomfortable with using a lesser known bulk brand name, then spend the extra coin on a more expensive well known name brand like Prestone..