Brakes: Silicone brake fluid color

[studefan]

The brake system on my 64 Lark was rebuilt a few years ago by a reputable shop before I purchased the car.

I have the receipts though and it mentions silicone brake fluid was used.

I replaced an old brake hose and noticed the fluid to be a light yellowish color similar to traditional brake fluid.

Yesterday, I purchased a new bottle of silicone brake fluid from the parts store and it has a blue tint.

Did silicone brake fluid come in the two different colors? Is it OK to pour this into the brake system?

Thanks for your thoughts.

[Skip Lackie]

The DOT5 stuff I bought 20 years ago was the yellowish color. The stuff I have bought more recently was a sort of a purplish color. Not sure if the difference was due to the manufacturer or that the whole industry changed the color to prevent mixing with DOT3/4. Take a spoonful or two of the yellow stuff out of the master cylinder and mix it in a jar with some of the blue fluid. If they mix and don't separate, you're probably okay.

[53k]

The DOT5 stuff I bought 20 years ago was the yellowish color. The stuff I have bought more recently was a sort of a purplish color. Not sure if the difference was due to the manufacturer or that the whole industry changed the color to prevent mixing with DOT3/4. Take a spoonful or two of the yellow stuff out of the master cylinder and mix it in a jar with some of the blue fluid. If they mix and don't separate, you're probably okay.

The gallon I bought 30+ years ago was purple.

[studefan]

Thanks guys. Hope to see both of you at Gettysburg. Jeff

[WCP]

All Dot 5 fluid is purple but if the fluid is packaged in a polyethylene bottle, the purple dye is adsorbed into the white pigment of the bottle, leaving the fluid a light yellowish color. This doesn't affect the quality of the fluid. I just finished setting up a Lark with PDB and silicone fluid that I had purchased many moons ago and it has lost all of its purple dye. Incidentally, when bleeding out a system with new lines and cylinders, I always filter the "spent" fluid thru a couple coffee filters and use that for any top up necessary later. You can't do that with Dot 3!

[Welcome]

The gallon I bought 30+ years ago was purple.

Was it purchased through military surplus sources?

30+ years ago, DuPont actually referred to that color as "Violet." Also back then the military was purchasing it in 55 gal. drums then often transferring it to smaller, unlabeled, containers. After many incidents over many years of getting "Violet" colored silicone brake fluid mixed up with "reddish" colored transmission fluid in their HMMWVs, they specified silicone brake fluid be "blue."

Bottonline; What color you have depends a lot on where and when you got it.