Brake Fluid

[moestr7v8]

Hi all, time for me to ask a silly question, how can I tell what brake fluid is currently in my master cylinder, mineral or synthetic, as I need to bleed and replace the fluid as one of the rear cylinders seized and I think I may have boiled the fluid, considering how hot the drums were and the way the paint was burnt off the drum.
Also can anyone tell me the size of Princess four pot caliper bleed nipples or where they can be purchased from.
Any help will be much appreciated.
Cheers
Moe

[Hasbeen]

Moe, I'd suck some out of the reservoir with a plastic hose, put a bit into 2 seperate glasses, & mix in some fluid you have, or wish to use, & watch for a reaction. Use if no reaction.

Hasbeen

[FI Spyder]

That's the scientific way to do it. I'm assuming brake fluid standards are the same, world round. Our cars call for Type 3, type 4 has higher boiling point and are interchangeable, if you are doing hard driving (breaking) type 4 might be better but personally never had a problem with type 3. Type 5 is silicone based, doesn't absorb moisture, is purple in colour and stays that way (at least in the instances I've seen it) and is the only type that is not compatible with others. It won't wreck paint. Type 5.1 is similar to 3 and 4 but with higher boiling point. The are a lot of old wives tales (urban legends) about 5 wrecking rubber seals but that was due to the type of rubber used when first introduced. If you are going to type 5 because you don't want it to wreck your paint or because you don't want to have to change it (doesn't absorb water) or because of it's higher lubricity, it's best done on a system where rubber seals have been changed and lines blown out so there is no cross contamination. It has more compressibility than the others but I've been of the mind that braided steel lines would make up for any of this. As you go up in number (and boiling points) they get more expensive.