I have read many articles about Dot 5 brake fluid and it seems like it might be good for cars that are kept for a long time with minimum maintenance required. So I am wondering if anyone has converted from Dot 3 to Dot 5 in their Fiero or other cars. Was it difficult to do? How long ago did you do it? Would you suggest doing it?

Thanks.

By the way Dot 5 and Dot 5.1 brake fluid are not same.

quote Originally posted by Fiero.1984: Would you suggest doing it?

For a race car or dedicated off-road vehicle? Maybe.

For a Fiero? No. I studied this many years ago (in an aviation context) and concluded that it's a bad idea. DOT5 is silicone-based, which is incompatible with glycol/ether-based DOT3/DOT4/DOT5.1 fluids, and DOT5 is probably incompatible with all the rubber seals and hoses in the Fiero brake system. It's hard enough to find repair seals for existing Fiero brake components; it might be impossible to find equivalent seals compatible with DOT5.

As for long-term storage, it is true that DOT5 fluid is not hygroscopic ... i.e. it will not absorb water from the atmosphere, reducing the boiling point of the resulting solution. But water from the air will still enter a DOT5 system, with three unexpected and potentially dangerous results: 1) Since it is insoluble in DOT5, the water will form discrete globules, which will tend to bunch together into bigger globules. Of course, being pure water the boiling point of these globules (212° F at standard atmospheric pressure) is much lower than the surrounding DOT5 fluid. 2) Where the water globules are in contact with metal surfaces (steel brake lines and fittings, caliper bodies, etc.) there is likely to be accelerated corrosion. 3) The freezing point of the water globules will be 32° F, and a water globule may eventually grow large enough to completely obstruct a brake line when frozen.

[This message has been edited by Marvin McInnis (edited 08-04-2013).]

I switched to DOT 5 3 years ago (and approx. 40k miles) when I rebuilt my entire brake system: Calipers, hoses, master cylinder. My buddy works for Mercedes and since we did the work at his dealer... DOT 5 was all they use...we pumped it through.

Bled it through my clutch system too when I replaced the clutch master and slave. With the clutch system i DID have a problem before replacing with DOT 5. Prior to replacement, when driving under heavy load, the heat would cause the DOT 3 fluid to boil and I'd lose my pedal. I'm sure that this happened because the DOT 3 was old and had been in there for several years.

Now that I read Marvin's post..i'm a little concerned. Though I have not had a single problem with my brake or clutch systems (knock on wood) and I inspect for leaks etc. every 3k miles when I put the car on the rack to change oil and rotate tires. I wonder what issues are lurking that i'm not gonna notice until it's too late!? I drive my car every day. Too late to switch back to DOT 3. Guess i'll just have to keep my eye on things.

donuteater306 - "I switched to DOT 5 3 years ago (and approx. 40k miles) when I rebuilt my entire brake system: Calipers, hoses, master cylinder. My buddy works for Mercedes and since we did the work at his dealer... DOT 5 was all they use...we pumped it through. "


Thanks for the information.

Almost everything that I have read says that it is best to make the change to Dot 5 after replacing all of the components like you did. Since you have new components the seals and everything is only 3 years old, you will probably not have any problems. I have read of other people doing exactly what you did and not having any problems after a much longer time than 3 years. I was hoping to find someone who had done the conversion without a complete rebuild of the brake system. If I do a complete replacement like you did, I would certainly use Dot 5.

Here is my contribution...

Marvin is intelligent.

With that said, I have replaced my Dot 3 with Dot 5 is more than a few builds. I drove an 89 Mustang with engine, suspension, and braking mods for over 70,000 miles and 7 years after completely installing a new braking system into her. Never had Dot 3 through it.

My current 87GT I did the same thing to. ALL new components, including all brake lines this time. I run Dot 5, have 5 years and 20,000 miles on the build. I am one of the most OCD folks when it comes to life. I too inspect everything annually, and keep a close eye on things as the season progresses. I will continue to "buck the rules" and install Dot 5 on all of my fresh builds. I do not mix fluids though.

Edit to add: While I have only one ticket in my 26 years on the road , I do drive my builds. Meaning that I enjoy heavily spirited driving when the roads, traffic, and conditions allow. I do a lot of mountain driving now with my GT, and she performs exactly as she should.

[This message has been edited by Tony Kania (edited 08-04-2013).]

See my Cave, Brake Fluid

Fiero/DOT3/4/5.1 parts are not made to use DOT5 fluid. For 1, DOT5 doesn't lube the parts like ethylene fluids and can cause seal failures.

You Never get all old fluid out of system. You need to replace whole system... MC, Calipers, lines, Combination valve, and anti-lock parts on cars that have it.

Tiny bit left of old fluid and any water get into system won't mix w/ DOT5 and will seek low areas then can eat metal, Waiting to boil, etc.

Use DOT4 or 5.1 that mixes w/ leftover DOT3.

Racing? Suggest you read the rules on many classes.

Non-silicon is fine for years of storage.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

quote Originally posted by donuteater306: My buddy works for Mercedes and since we did the work at his dealer... DOT 5 was all they use...we pumped it through.

I wasn't there, so I can't possibly know for sure, but that was almost certainly DOT 5.1 brake fluid, not DOT 5! The two are not the same, not even close. A quick search seems to confirm that no production Mercedes has ever used DOT 5 fluid.

DOT 5 is a silicone-based fluid. It is not compatible with DOT 3, DOT 4, or DOT 5.1 fluids.

DOT 5.1 is a polyethylene glycol-based fluid that is compatible with DOT 3/4 fluids but has performance characteristics (particularly boiling points) similar to DOT 5. Another significant benefit of DOT 5.1 vs. DOT 3/4 is that polyethylene glycol is relatively non-toxic to humans and animals. Some polyethylene glycols are even used in pharmaceuticals, cosmetics, and in small quantities as food additives. Here is a link to the MSDS for Wagner's DOT 5.1 brake fluid.

Repeat after me: "DOT 5.1 is not DOT 5!"

[This message has been edited by Marvin McInnis (edited 08-04-2013).]

I run ATE Super Blue brake fluid in most of my cars.....flush every two years as it is hydroscopic.

Dave

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www.hausofguru.com

quote Originally posted by Marvin McInnis: DOT 5.1 is a polyethylene glycol-based fluid that is compatible with DOT 3/4 fluids but has performance characteristics (particularly boiling points) similar to DOT 5. Another significant benefit of DOT 5.1 vs. DOT 3/4 is that polyethylene glycol is relatively non-toxic to humans and animals. Some polyethylene glycols are even used in pharmaceuticals, cosmetics, and in small quantities as food additives. Here is a link to the MSDS for Wagner's DOT 5.1 brake fluid.

Boil point is right but safe/safer?
Polyethylene glycol is not Propylene Glycol. (all wiki)

Propylene Glycol is used in many food products and Low tox Coolant, like Sierra.
Polyethylene glycol is used to make laxatives.
____ethylene glycol often is dangerous.
Even when whatever base by itself is safe other Additives/Ingredients can/will irritate poison etc.

Example from MSDS you posted has 2 versions of Triethylene glycol

code:

---

1 PRODUCT AND COMPANY IDENTIFICATION
Product Name: Dot 5.1 Brake Fluid 
Manufacturer Name:
Federal-Mogul World Headquarters 
2 HAZARDS IDENTIFICATION
OSHA Regulatory Status: This product is hazardous according to OSHA 29CFR 1910.1200.
3 COMPOSITION / INFORMATION ON INGREDIENTS
Chemical Name                                       CAS-No.    Concentration*
†Triethylene glycol monomethyl ether borate ester   30989-05-0 40 - < 70%
†Triethylene glycol methyl ether                    112-35-6   15 - < 40%
†2-Aminoethanol                                     141-43-5   0.1 - < 1%
* All concentrations are in percent by weight unless ingredient is a gas. 
Gas concentrations are in percent by volume.
† This chemical is hazardous according to OSHA/WHMIS criteria

---

I purposely did not say "safer." The key word is relatively non-toxic. While I wouldn't recommend drinking DOT 5.1 brake fluid or (any other industrial chemical, for that matter), it appears to be less toxic than DOT 3/4 fluids. From the Wagner MSDS for their DOT 5.1 brake fluid:

code:

---

Product Name:  DOT 5.1 Brake Fluid
...
Emergency Overview

Physical State: Liquid

Color: Yellow

Odor: Mild

CAUTION!  
May cause skin and eye irritation.

Potential Health Effects

Inhalation: May cause slight respiratory tract irritation.

Eye Contact: May cause eye irritation.

Skin Contact: May cause skin irritation.

Ingestion: May cause discomfort if swallowed. 

---

By contrast, here is the same section of the MSDS for Wagner DOT 4 brake fluid:

code:

---

Product Name:  DOT 4 Brake Fluid
...
Emergency Overview

Physical State: Liquid

Color: Yellow

Odor: Characteristic

WARNING!
Causes severe skin and eye irritation. May be harmful if swallowed.

Potential Health Effects

Inhalation: May cause slight respiratory tract irritation.

Eye Contact: Severely irritating to eyes. Exposed individuals may experience eye tearing, redness, and discomfort.

Skin Contact: Severely irritating to skin. Exposure may cause redness, itching and inflammation.

Ingestion: May be harmful if swallowed. May cause central nervous system depression.

Chronic Health Effects: May cause central nervous system depression. May cause damage to the liver and kidneys

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[This message has been edited by Marvin McInnis (edited 08-05-2013).]