DOT 2 Brake Fluid use?

[Ivan_B]

I am wondering, what was the original brake fluid in use for our cars in the 40-50? My 40 manual simply refers to is as "MoPar brake fluid". I did find some images of the old MoPar heavy duty brake fluid tins. They don't list the ingredients but, based upon the listed specs (non-corrosive, flammable, up to 400F operating temperature) it looks like the good-old DOT 2 (castor oil + alcohol). Is that right?

 

The reason I am asking is because I am thinking about switching to DOT 2, for its non-corrosive and non-hygroscopic properties. I have drum brakes (no need for the extra high boiling point) and do not operate the car in cold weather (no issues with the fluid getting a bit thick) 🤔

[Sniper]

DOT 2?  I wouldn't even know where to get it.  None of the brake fluids are corrosive, in and of themselves.  It's the moisture that gets into them that can cause issues.  Which is why you are supposed to flush them regularly.

[desoto1939]

I was always told not to spill any brake fluid on anything that is painted because it will ruin the painted surface. If this is true then the brake fluid excect for DOT5 will remove and or stain your painted parts.

 

This is one of the reasons I use DOT 5 because of the high humidity aspects here in Eastern PA and DOT 5 does not draw moisture into the fluid.  I am not concerned about the amt of heat that the fluid can protect but for the moisture aspect.

 

I have been using DOT5 for over 35 years in my 39 Desoto.

 

Rich Hartung

Desoto1939@aol.com

[Ivan_B]

Maybe I am not using the correct terminology here. I do not like the brake fluid eating away the paint, etc. It really does, I've spilled some before ) I suspect it does that regardless of having absorbed any water, because my spilled liquid came right from the new sealed bottle.

Has DOT 5 been available for that long, already? What year is it, again? I must be getting old 🤣

 

The DOT 2 can be easily mixed yourself (done that before). The common formula appears to be 50/50 castor oil and butyl alcohol. But, it is not suitable for disk brakes (too hot) and it can get "thick" in very cold weather. Last time I've been playing with some in the bottle, it was still visually maintaining its fluidity at 5F, so this is well beyond my typical Florida driving needs.

[desoto1939]

16 minutes ago, Ivan_B said:

Maybe I am not using the correct terminology here. I do not like the brake fluid eating away the paint, etc. It really does, I've spilled some before ) I suspect it does that regardless of having absorbed any water, because my spilled liquid came right from the new sealed bottle.

Has DOT 5 been available for that long, already? What year is it, again? I must be getting old 🤣

 

The DOT 2 can be easily mixed yourself (done that before). The common formula appears to be 50/50 castor oil and butyl alcohol. But, it is not suitable for disk brakes (too hot) and it can get "thick" in very cold weather. Last time I've been playing with some in the bottle, it was still visually maintaining its fluidity at 5F, so this is well beyond my typical Florida driving needs.

Ivan:  I purchase a tool and there is a posting about it in the Show your tools posting. It cost me several dollars but it tests the brake fluid for moisture. Even a  bottle on DOT3,4,5 that has been opened and the lid put back on tightly will still get moisture back into the bottles. I tested some DOT3 that has been on my self and had been opened

and i tested it and there was moisture to the point that i decided to get a brand new bottle. I then tested on my DOT5 bottle that also had been opened and resealed and this did not have any moisture according to the pen and that bottle had been opened well over a year ago.

 

rich hartung

desoto1939@aol.com

[Dan Hiebert]

I don't know how much castor oil and butyl alcohol costs, I'm assuming not very much.  DOT5 is relatively expensive, I think I paid a bit over $30 for a quart about 20 years ago.  But, DOT5 is readily available, does not attract moisture, and does not damage paint (if those are your concerns), and in a well sealed system, lasts a very long time.  Personally, when it comes to safety things like the brakes, I wouldn't try to out-engineer something that is already proven to work well. 

[FarmerJon]

3 hours ago, Ivan_B said:

Maybe I am not using the correct terminology here. I do not like the brake fluid eating away the paint, etc. It really does, I've spilled some before ) I suspect it does that regardless of having absorbed any water, because my spilled liquid came right from the new sealed bottle.

Has DOT 5 been available for that long, already? What year is it, again? I must be getting old 🤣

 

The DOT 2 can be easily mixed yourself (done that before). The common formula appears to be 50/50 castor oil and butyl alcohol. But, it is not suitable for disk brakes (too hot) and it can get "thick" in very cold weather. Last time I've been playing with some in the bottle, it was still visually maintaining its fluidity at 5F, so this is well beyond my typical Florida driving 

Homebrew brake fluid, now that is a good one!

The master cylinder is under the floor, not much paint to ruin there. Usually when I have spilled DOT 3-4-5.1 I wipe it up right away, ideally with a damp rag. I have not had any major issues with paint loss. Yes it absolutely will turn paint to soft goo, but it takes more than a few seconds, and there is plenty of time to clean it up. 

Just run silicone DOT 5 if you are worried about it. At least it has a known boiling point and tested properties. 

 

I have always flushed Drum brake cars with DOT 4 or 5.1 and have enjoyed having less brake fade in the rolling hills and country roads of my area. I just flush it every 2 years or so. Not much work, and a cheap upgrade.

Edited March 15 by FarmerJon

[Sniper]

1 hour ago, FarmerJon said:

Usually when I have spilled DOT 3-4-5.1 I wipe it up right away, ideally with a damp rag. I have not had any major issues with paint loss.

 

Or flush it with a hose to make sure you get it all.  The paint issue isn't what's called corrosion and most definitely was not what I was talking about.

[TodFitch]

2 hours ago, FarmerJon said:

Homebrew brake fluid, now that is a good one!

The Operators Manual (i.e. owner's manual) for my 1933 PD has a recipe for making brake fluid. They warn to only to use the home made stuff in an emergency and then get the system flushed and refilled with approved Chrysler brake fluid as soon as possible as there will be acids that will damage the brake system over time. Remember that back in 1933 most cars still had mechanical brakes and so the supply stores in smaller or rural locations might not stock brake fluid so if you were out in the middle of nowhere and needed brake fluid you could make some from things available from the local pharmacy.

 

I don't know about modern automotive paint that uses hardeners, but for old fashioned nitrocellulose, nitrocellulose, alkyd, and acrylic paints DOT 3 brake fluid is a very quick and effective paint remover.

[Ivan_B]

53 minutes ago, TodFitch said:

The Operators Manual (i.e. owner's manual) for my 1933 PD has a recipe for making brake fluid.

Would you mind posting what it says? Just curious. Because the only one you can mix DIY, I know of, is castor + butanol.

I understand that this sounds pretty sketchy, but back then it was actually the commercial fluid recipe, similar to how you would buy antifreeze today - either 50/50 mix, or some concentrate and distilled water

 

Thus far, it looks like regardless of what non-glycol fluid I switch to, I will need to replace the rubber and flush the system. I do need to replace the rear metal lines, due to corrosion, concerns. Not sure if I want to go a full rebuild, at this point, though. 🤔

Edited March 15 by Ivan_B

[TodFitch]

2 hours ago, Ivan_B said:

Would you mind posting what it says? Just curious. Because the only one you can mix DIY, I know of, is castor + butanol.

I understand that this sounds pretty sketchy, but back then it was actually the commercial fluid recipe, similar to how you would buy antifreeze today - either 50/50 mix, or some concentrate and distilled water

 

Thus far, it looks like regardless of what non-glycol fluid I switch to, I will need to replace the rubber and flush the system. I do need to replace the rear metal lines, due to corrosion, concerns. Not sure if I want to go a full rebuild, at this point, though. 🤔

 

 

Quote

 

General

The master cylinder reservoir on the top of the master cylinder should never be less than half full of genuine Plymouth Hydraulic Brake Liquid, which is obtainable at any authorized Plymouth Service Station. This should be used to the exclusion of all other liquids, but if for some reason the genuine liquid is not available for an immediate requirement, a suitable substitute liquid may be made by thoroughly mixing equal parts of medicinal caster oil and No. 5 denatured alcohol free from acid (wood alcohol should never be used). This formula should only be used when the genuine Plymouth Hydraulic Brake Liquid is not available, and it is important that the improvised liquid be entirely drained from the system as soon as possible and replaced with Plymouth Hydraulic Brake Liquid. Plymouth Brake Liquid is make in very much the same manner, but certain chemicals are added by a very lengthy, as well as difficult, process which neutralizes acids found in the formula prescribed above.

 

 

[Veemoney]

17 hours ago, Dan Hiebert said:

I don't know how much castor oil and butyl alcohol costs, I'm assuming not very much.  DOT5 is relatively expensive, I think I paid a bit over $30 for a quart about 20 years ago. 

I recently purchased a quart of DOT 5 from O'Reilly Auto parts about 2 weeks ago. Motor Medic brand and price was best deal I found at the time, $32.99 plus tax if anyone is looking. 2 years ago I picked up some from Napa when they had a 50% off deal. Always good to go online and check for the best prices.

[Sniper]

13 hours ago, TodFitch said:

equal parts of medicinal caster oil and No. 5 denatured alcohol free from acid (wood alcohol should never be used).

 

Err, denatured alcohol, at least these days, usually has "wood" alcohol in it (methanol).  Back during Prohibition, same time frame, the use of methanol to make denatured alcohol was mandated by US law.  These days, there are other options used, so check if you are going this route. 

[Ivan_B]

Yes, I had to look up what denaturated alcohol actually is. What a waste of ethanol 🤣

[GTfastbacker]

 

I try to imagine how brake fluid would splatter over the paint if the vehicle had an underfloor brake cylinder. All the images that come to mind are comic-style. Sorry, that's probably because of my vivid imagination.

 

Joe

Edited March 24 by GTfastbacker

[Ivan_B]

I just have a personal bias against DOT 3-4 fluid. You can spill it when topping off the cylinder, when working on hoses/lines, it can leak all over the wheels due to a poor connection, etc. I did check how much butanol is going for, these days, so I might just switch to the Dot-5 silicon fluid instead, when I get to do the brakes.