"Typing" existing brake fluid
09-09-2007, 07:35 PM
#1
Le Mans Master
Thread Starter
"Typing" existing brake fluid
Hi
How do I tell what type brake fluid is in my car. I have been told it can be told by taste but that tells me little
Also what fluids would be compatible. I don't know what is in there and I need to bleed the system.
Thanks in advance
Doug
How do I tell what type brake fluid is in my car. I have been told it can be told by taste but that tells me little
Also what fluids would be compatible. I don't know what is in there and I need to bleed the system.
Thanks in advance
Doug
09-09-2007, 07:47 PM
#2
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Been there, done that. First off, silicone (DOT5) is not always colored. The way I did it was to take some of the old fluid out of the system and mix it with DOT5 (preferably newer, colored stuff and, no, DOT4 is different). If it mixes uniformly it's DOT5. As a second test you can mix the old stuff with a litter water. DOT3 will absorb water while DOT5 will not.
I used baby food jars for the mixing. Buy one or two small jars, eat or dump what is in them and wash them out.
I used baby food jars for the mixing. Buy one or two small jars, eat or dump what is in them and wash them out.
09-09-2007, 07:48 PM
#3
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Take a sample (about 2 oz.) from the master cylinder reservoir and put it in a small glass container (like a jelly jar); add an equal amount of water, cap it, shake it well, and set it on the bench. When it settles down, if it has formed two distinct layers, it's DOT5 silicone fluid. If it hasn't formed layers and appears as a single fluid, it's DOT3/4 conventional fluid.
DOT5 silicone fluid is ONLY compatible with itself, and the same is true of DOT3/4 fluid; they will NOT mix.
DOT5 silicone fluid is ONLY compatible with itself, and the same is true of DOT3/4 fluid; they will NOT mix.
09-09-2007, 11:02 PM
#5
Taste ?!?!? 
Did bubba tell you that? I would not consume ANY amount of break fluid! Had a few numnuts in the Army drink break fluid to get high....renal failure followed shortly after.
Did bubba tell you that? I would not consume ANY amount of break fluid! Had a few numnuts in the Army drink break fluid to get high....renal failure followed shortly after.
08-11-2008, 10:40 PM
#6
change dot3 to 5 in a 60.
Take a sample (about 2 oz.) from the master cylinder reservoir and put it in a small glass container (like a jelly jar); add an equal amount of water, cap it, shake it well, and set it on the bench. When it settles down, if it has formed two distinct layers, it's DOT5 silicone fluid. If it hasn't formed layers and appears as a single fluid, it's DOT3/4 conventional fluid.
DOT5 silicone fluid is ONLY compatible with itself, and the same is true of DOT3/4 fluid; they will NOT mix.
DOT5 silicone fluid is ONLY compatible with itself, and the same is true of DOT3/4 fluid; they will NOT mix.
Last edited by stratplus; 08-13-2008 at 07:42 AM.
08-12-2008, 03:55 AM
#7
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St. Jude Donor '07
Bill
08-12-2008, 08:45 AM
#8
Drifting
If you are using DOT 3 or 4 now and are not planning on a complete redo of the entire brake system, simply refill with a quality DOT 4 such as Castrol LMA and flush until you get clean fluid at all the bleeders. Mixing of silicon and non-silicon fluids, even in trace amounts does not work, neither does the use of silicon fluid with seals that have spent their lives with DOT 4 or 5. This is a true safety issue if you are to have a reliable brake system!
08-13-2008, 08:16 AM
#10
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C2 of Year Finalist (track prepared) 2019
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