was gonna post this on the current brake thread, but felt this deserved its own thread for archive sake.

is there a FORMULATION difference between fluids labelled DOT 3 and DOT4? obviously there are minimum standards set to be labelled either 3 or 4, (and fluids labelled "DOT 3/4" are just so consumers dont question if the DOT 4 fluid can work in their DOT 3 system) but is there an actual difference that separates the two? or is it just make the whatever non-silicone fluid and label it as high as it passes?

i dont seem to be able to find the info on the net. just a lot spewing out the min specs.

 

http://www.raceshopper.com/brake_fluid.shtml
i think the higher the boiling point of the fluid the easier for the fluid to lower the boiling point by letting in moister when you open the master cylinder. from what i read not on this link but in the past opening the master cylinder can let the moisture enter the fluid and up to 2% on dot 5 fluids can affect dramatic results in lowering the temperature by 100degrees or more. so lower the fluid it's safer for the street. you really don't need dot 5 unless you are on the track pretty much.

 

The difference between DOT 3 and DOT 4 is negative DOT 1

 

i could have said that but didn't feel simple