Difference between DOT3 and DOT4? Will it hurt?

[jordan172005]

I noticed in my master cylinder that the brake fluid in there is pretty dark in color like a dark brown. I have a big container with DOT3 brake fluid in it and was wondering if I could use that in my GS500E? My friends bike ( KZ700 ) called for DOT3 but mine calls for DOT4. I did a search but didn't find anything...

[darb85]

yes it will hurt it.  Dot four is either thicker or thinner(dont remeber which) and your breaks will not work correctly.  Also, It is a bit darker than Dot 3 so it may not be dirty,  any Autoparts store will have Dot 4 for like 2 bucks for a bottle that will last you forever

[dgyver]

Dot 3 and Dot 4 can be mixed without problems. Do not mix with Dot 5. If the container has been opened for very long, buy new stuff. I only buy small containers as it is hygroscopic and will go bad quickly.

[gsJack]

Dot 4 has a higher boiling point than Dot 3 but they will mix OK.  I use the Dot3/4 SYN type that meets both specs and mixes with both.

http://www.valvoline.com/pages/products/product_detail.asp?product=51

[debtman7]

Dot 4 has a higher boiling point than Dot 3 but they will mix OK.  I use the Dot3/4 SYN type that meets both specs and mixes with both.

http://www.valvoline.com/pages/products/product_detail.asp?product=51

I would highly recommend that as well, seeing as in my search through various auto parts stores I couldn't find any DOT4 fluid other than Dot3/4 synthetic

[gsJack]

Dot 4 has a higher boiling point than Dot 3 but they will mix OK.  I use the Dot3/4 SYN type that meets both specs and mixes with both.

http://www.valvoline.com/pages/products/product_detail.asp?product=51

I would highly recommend that as well, seeing as in my search through various auto parts stores I couldn't find any DOT4 fluid other than Dot3/4 synthetic

Good choice.   

No doubt the Dot 3 would be adequate for everyday riding around but it could boil under extreme conditions.  A few years ago with the old 97 GS, I turned my front rotor blue a couple times playing in the mountains.  I was using the Dot3/4 syn and didn't loose the brakes due to fluid boil but the front brake was gone the one time due to brake lining fade due to the heat.  I have since switched to HH pads and wouldn't expect the fade away again but I have also slowed down a bit and quit going to the mountains.  I still like the grip of the HH pads whether or not I still need them.   

Dot 3 boils at just over 400F and Dot 4 boils around 450F.  The Dot3/4 syn boils at 500F so why not use it for the extra buck a small container costs.

[Jace009gs]

I think DOT 5 is that green sludge stuff.....either way it's over kill


+3 on the Valvoline DOT3/4 synt.

[pbureau69]

yeah valvoline  isthe one I use on all my vehicules +3 big time

as for open containers, if it has been open (broken seal) more than a month, toss it and get a fresh bottle (it absorbs humidity from the air and that can be bad, but will make a difference between good strong brakes and "spongy brakes".

[darb85]

thatll teach me.  I was always told never to mix the two?? oh well. sorry for bad advice!

[ducati_nolan]

If the jug has been laying arround for a while it's probally no good anyways, so if you're going to buy some new stuff just get a little bottle of dot 4. It's cheap and you'll have more than enough to flush out both your front and rear systems. Don't bother getting the expensive synthetic motorcycle stuff. Just get the cheapest dot 4 at the auto parts store.

[TragicImage]

DOT 5.1  Just for the crazy overkill... and it mixes with anything except DOT5