AirSpeed VW Community Forums
Technical => Brakes Forum => Topic started by: Swartz on May 24, 2005, 05:58:12 PM
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What dot brake fluid should i run in my car? my friend was telling me to run dot 5 because its silicon based and will resist water and has a higher boiling point...when i went to go look at it at lordco its liek 15$ for a tiny bottle...is it worth it?
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Dot 3 is good enough. If your really picky about boiling point you should get some heavy duty ford brake fluid which has a phenominal boiling point.
If you really want to get fancy you can buy DOT 5.1 which is still polyglycol \"regular\" brake fluid.
If you use silicon your gonna have a spongy pedal and YOU MUST FLUSH your current \"regular\" dot 3 or 4 since silicon is not compatible with polyglycol based brake fluid.
Bruce Tweddle likes his silicon DOT 5 stuff. Everyone has a preference.
I'm just using DOT 3 in my 65 and I never have any brake fade with my driving habits. If your more into auto x then I'd think about dot 4 or 5
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ATE Blue. I think it's DOT 4
As stated... if you switch to DOT 5 you must flush the system.
I've heard the only real advantage to DOT 5 is it won't damage the paint.
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With DOT 3 or 4, it absorbs moisture out of the air. If you check your fluid now in any car it will be brown or black. This indicates it is horribly saturated with water. This is why all car makers tell you to purge the system every 2 years.
I hate bleeding the brakes, so I converted 2 of my cars to DOT 5 silicone fluid. One was 12 years ago, the other over 4 years ago. The fluid in both is still perfectly clear.
The only downside is that you technically have to dissassemble all your brake cylinders and wash off all traces of the old DOT 3 fluid because the two fluids are not compatible. I didn't do that, instead, I flushed methanol through the components and dried them out with compressed air. Repeat 3-5 times.
I did a test once by pouring some DOT 3 into some silicone fluid. They were like oil and water.
The naysayers will say VW components are not compatible with DOT 5. In 12 years I think I would have seen a problem.
The pedal is slightly spongy, but so what? Hit the brakes, the car stops. What else needs to happen? Not one person that has driven my car has noticed the difference. Hit the brakes, the car stops.
Don't get your DOT 5 fluid from Lordco, get it from CDN Tire. The 500ml bottle at CDN Tire is about half the price of the 375ml bottle at Lordco. I found that the fluid that came out of the system was so clean (and since it doesn't absorb water...) that I just recycled it back into the MC on the initial bleeding. Once the system was air free, I bled through virgin juice. This kept the cost down.
I don't think the boiling point of the fluid you use is relavent on the street. You will never use your brakes repeatedly enough to come even close to causing the fluid to boil. At the most you might do one hard brake from high speed every few days, then you'll drive slowly. It's not like a race track where you haul the car down from high speed at the end of the straight on every lap.
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Thanks for the info, when i put my brakes back together im goign to go ahead and use the dot 5
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i was just reading this and was curious if DOT 5 will infact not harm paint?
i think that in itself would be a great selling point.
not that i ever mean to but i always spill some fluid when bleeding brakes
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I've debated with bruce on this one.
I will never use dot 5 because its a spongy feel that I absolutely HATE. If it doesn't absorb water there are guys complaining of water in the brake system rusting out certain areas where it \"pools\" in the closed system.
I like polyglycol based dot 3 and 4 and even 5.1 because its a simple flush and will provide good feel to the brake system. If your worried about boiling points the ford motorcraft is the cheapest and highest boiling point dot 4 available.
If I did use dot 5 I would still flush my brakes just because of water contamination not mixing as a solution with the silicon based stuff.