Questions Re: DOT 5 Silicone Brake Fluid

[Don Z.]

After reading many posts and the archives I have decided to change my '66 over to silicone Dot 5. A few questions please.

Isn't all silicone Dot 5 purple? and Is all silicone Dot 5 equal or is one brand prefered over others?

Of the few places locally, I can only find little bottles of silicone Dot 5 and most of the places don't know what color it is yet alone anything about it.

Thank You

[Joe L.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

After reading many posts and the archives I have decided to change my '66 over to silicone Dot 5. A few questions please.

Isn't all silicone Dot 5 purple? and Is all silicone Dot 5 equal or is one brand prefered over others?

Of the few places locally, I can only find little bottles of silicone Dot 5 and most of the places don't know what color it is yet alone anything about it.

Thank You

Don-----


DOT 5 silicone brake fluid is dyed purple. I've never seen it any other color. It's probably part of the DOT spec. However, it does not forever remain purple after it's installed in the car. For some reason, after awhile the purple dye changes to a yellow color-----much deeper yellow than the normal color of most DOT 3 brake fluid. I don't know what factor causes the dye color change. I don't think it indicates any actual deterioration of the fluid, though.

I think that most DOT-5 fluid is manufactured by only a few large chemical manufacturing companies. Dow is one of them. However, it's re-packaged and sold under lot of brands.

[Daniel S.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

I believe all DOT 5 brake fluid is purple in appearance when new. Don't think there is any difference from one brand of DOT 5 to another brand. Most corvette brake vendors sell larger bottles of the product then you will find at local auto parts stores. Corvette Central sells a quart bottle for about $24.

[Don Z.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

Thank You Joe & Daniel. That is what I thought from reading posts but a few locals said it was clear. I wanted to see if I could find larger bottles local in lieu of going to aftermarket and paying freight. Thanks again, appreciate it.

[Fenwick B.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

I put Silicone Brake Fluid in my 55 a few years ago when I installed the new brake system on it. I got mine from NAPA. It is NAPA brand, and they had to order it from their distributor. It only took a few days to get it. I didn't remember that it was purple so I went and looked at the spare bottle that I have. Yep. it's purple. I had to buy a carton of 6 pints of it, for them to order it for me. Fenwick

[David K.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

In my area of Ohio, Advance Auto Parts, has it on the shelves.

[John F.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

O'Reilly's Auto parts have it on the shelf. GUNK brand and is $7.99 per 11 oz. bottle. That's what I used...John

[Don Z.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

Thanks for the imput from everyone. I have read somewhere on this board about how much to buy when changing everything over but I can't seem to put my finger on it now. Soooo how much is enough to buy...1 / 2 quarts ? or a quart and a smaller bottle ? Thank You

[Jim D.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

However, it does not forever remain purple after it's installed in the car. For some reason, after awhile the purple dye changes to a yellow color-----much deeper yellow than the normal color of most DOT 3 brake fluid. I don't know what factor causes the dye color change. I don't think it indicates any actual deterioration of the fluid, though.

Any idea how it takes for this color change? The reason I ask is that I just changed my front brakes hoses and the fluid looked like it just came out of the bottle (purple).

[William G.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

Don, I just changed my brake fluid to silicone when I changed brake lines on my 66. I blew out the calipers thoroughly, and needed just about 1 1/2 quarts to fill ,flush and bleed the system. I probably used a little more than needed to make sure that any old fluid was purged, but I am sure that you will need over 1 quart and under two quarts if you are careful.

[Joe L.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

Any idea how it takes for this color change? The reason I ask is that I just changed my front brakes hoses and the fluid looked like it just came out of the bottle (purple).

Jim-----


I don't know just how long it takes for the color change. In fact, I think it's sort of "variable" but I don't know what causes the variation. When I first installed it in my 1969 many years ago, I know that, at least by a couple of years later it had changed to yellow. I have some that I purchased many years ago (at least 15), but left it in the factory sealed containers (with the plastic caps and aluminum seals). When I opened one of the containers a few years ago, it was yellow.

By the same token, I have a gallon size jug of Dow-Corning branded silicone 5 which was originally produced and packaged for the US Army. It's in a more-or-less clear jug that's never had the seal broken. It's still purple.

[Jim L.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

If you start with gravity bleeding and follow up with slow and careful traditional bleeding, you'll use less than 1 quart of fluid.

Jim

[Jim D.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

Jim-----


I don't know just how long it takes for the color change. In fact, I think it's sort of "variable" but I don't know what causes the variation. When I first installed it in my 1969 many years ago, I know that, at least by a couple of years later it had changed to yellow. I have some that I purchased many years ago (at least 15), but left it in the factory sealed containers (with the plastic caps and aluminum seals). When I opened one of the containers a few years ago, it was yellow.

By the same token, I have a gallon size jug of Dow-Corning branded silicone 5 which was originally produced and packaged for the US Army. It's in a more-or-less clear jug that's never had the seal broken. It's still purple.

The reason I asked is that the DOT 5 I bought from Corvette America in 1985 and installed in my 1960 is still purple both in the bottle and the car. I also bought some "Cartel" brand DOT 5 about 10 years ago for a 57 T-Bird I restored, and it's still purple, in the bottle, the car's long gone.

[Ken B.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

How do you get all the old fluid out of the system?

[Jim D.]

Re: Questions Re: DOT 5 Silicone Brake Fluid

How do you get all the old fluid out of the system?

The correct way is to remove the master cyl. and wheel cyl./calipers, flush the lines with alcohol, blow out with compressed air, and then rebuild all cylinders/calipers using DOT 5 to assemble.

Jim