Temperature ranges of brake fluids

[DRW1000]

I hope this issue hasn't been answered recently. I did a search but couldn't see the answer:

I have some bottles of DOT3 brake fluid with a boiling point of 550F. It is labelled for Fords and I believe Fords require that temperature range. Is there any reason why this fluid cannot be used in a GM that simply asks for DOT3? I know I have seen 478F and a third but I have this stuff on hand. I actually want to replace all the fluid in the system.

[TheSilentChamber]

The standards for DOT 3 is minimum wet boiling point of 284 F, dry 401 F. DOT 4 has a minimum of wet 311, dry 446, DOT 5 is a silicon base and does not asorb moisture and has a minimum boiling point of 500.

So to answer your question, if it calls for DOT 3, you can use any DOT 3.

[DRW1000]

Originally Posted by TheSilentChamber

The standards for DOT 3 is minimum wet boiling point of 284 F, dry 401 F. DOT 4 has a minimum of wet 311, dry 446, DOT 5 is a silicon base and does not asorb moisture and has a minimum boiling point of 500.

So to answer your question, if it calls for DOT 3, you can use any DOT 3.

Thanks for the response. I went back to my autoparts store and they had the following:

DOT3 - 401 F
DOT3 for Fords - 550 F
Dot 4 - 478 F

They also had a couple of Synthetics that I considered.

Ultimately I bought the 550 F Dot 3 for my Ford and the Dot 3 401 F for my Chevrolet (that did not specifiy any particular temperature).

I don't know a simple thing like this can be so confusing. Can the two different temperature rated Dot 3's be mixed?

[TheSilentChamber]

Yes but I'm not sure what your temp range would be. I have also never heard of fords having to use a higher temp rating.

[DRW1000]

I don't know why I think it needs to be so high it might just because this Version with the label "Premium Brake Fluids for All Ford Vehicles" @ 550 F is on the shelf. I even considered that maybe just one Ford model in recent years with severe under sized brakes might be enough for this type to have been specificed by Ford and my local parts store carries a brand that wanted to avoid any confusion (although in doing so they confused me). My manual Lists the specification 'ESA-M6C25-A and DOT3' and they call it ' High Performance DOT-3. Nothing in my opinion that really confirms or denys a special boiling point. On my GM I will use the 'standard' DOT-3 for no other reason except that it feels more right.

I am going to replace drums and pads and them flush the entire system. I have 1.5L of both types. I don't know how much fluid I will need so I guessed it.

Thanks for the help. Enjoy the weekend

[UncleBob]

DOT 3 and DOT 4 are standards based off of their heat range and chemical type. Don't know where you read that ford makes a DOT 3 that is that high of temp, because if it is that high, by definition it no longer is DOT 3.

DOT 3, 4 and 5.1 are all interchangable. 5.1 is synthetic, but still hydroscopic and will mix fine with 3 or 4. DOT 5 is all by itself though, won't mix with any other brake fluid.

[DRW1000]

Originally Posted by UncleBob

DOT 3 and DOT 4 are standards based off of their heat range and chemical type. Don't know where you read that ford makes a DOT 3 that is that high of temp, because if it is that high, by definition it no longer is DOT 3..

The type I bought isn't from Ford. It states that it is for Fords.

[DRW1000]

Originally Posted by DRW1000

The type I bought isn't from Ford. It states that it is for Fords.

Well curiousity got the best of me and I researched a bit. The boiling points are the minimum requirements. The FORD DOT3 may have a dry boiling point of 550 degrees which clearly exceeds DOT 3 and dot 4 requirements. However its wet boiling point is lower than 311 F which does not meeyt dot 4 But does meet DOT 3 requirements. For this reason it cannot be labelled as DOT 4.

It also absorbs water very quickly compared to standard DOT3 and 4. What this means is that 6 months after my putting this fluid in will result in me having a standard temperature range of DOT3 fluid in my vehicle.

[KiwiBacon]

Originally Posted by DRW1000

Well curiousity got the best of me and I researched a bit. The boiling points are the minimum requirements. The FORD DOT3 may have a dry boiling point of 550 degrees which clearly exceeds DOT 3 and dot 4 requirements. However its wet boiling point is lower than 311 F which does not meeyt dot 4 But does meet DOT 3 requirements. For this reason it cannot be labelled as DOT 4.

It also absorbs water very quickly compared to standard DOT3 and 4. What this means is that 6 months after my putting this fluid in will result in me having a standard temperature range of DOT3 fluid in my vehicle.

I've found similar ratings with DOT 4 compared to DOT 5.1

Some companies use DOT 5.1 to distinguish a fluid with higher boiling points than their standard DOT 4, yet some companies DOT 4's will exceed other companies DOT 5.1.

[Knap]

This may be helpful

http://www.stoptech.com/tech_info/wp...fluid_1a.shtml

[KiwiBacon]

Originally Posted by Knap

This may be helpful

http://www.stoptech.com/tech_info/wp...fluid_1a.shtml

I found the DOT fluid spec referred to in that article.
Took about half an hour and no I haven't read it yet.

http://www.nhtsa.dot.gov/staticfiles.../TP-116-04.pdf